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Teens use connected devices, namely smartphones, to communicate via texts and social media. This matters for marketers because teens are on the leading edge of technology and social media use.
Actionable Marketing Implication: Most US teens use smartphones to communicate and connect to the Internet.
Note: The research didn’t check for computer usage or availability at school or at a public library.
91% of US teen cell owners use text messaging, either via their mobile phone or an app or website.
Teen girls send an average of 40 texts per day and older teen girls send an average of 50 texts per day.
18% of teens from families earning less than $30,000 annually don’t text while less than 7% of teens from higher-earning families don’t text. Actionable Marketing Implication: Be available via text if you target the teen demographic!
What’s surprising is that video chat isn’t used at a higher rate since when free wifi (such as at Starbucks and NYC parks) is available, both computer and smartphone users aren’t charged for voice, data or text units.
Teens use connected devices, mainly smartphones, to go online and engage with their friends. US teens have an average of 145 friends on Facebook, that’s 10 less than their adult counterparts. Actionable Marketing Implication:  Teens are visual too!!! Provide images and videos on Instagram to attract their attention. 48% of Hispanic teens use Google+, 26% of US white teens use Google+, and 29% of African-American teens use Google+. 33% of US teen girls use online pinboards (including Pinterest and Polyvore) compared with 11% of US teen boys. 14% of US teens use Tumblr, a social media platform focused on microblogging visual content. Actionable Marketing Implication:  Teen girls use a variety of different visual platforms to express themselves.
11% of US teens with cell phones use sharing apps or sites that allow users to ask questions or to post confessional text or images anonymously. While teens continue to spend lots of time communicating with their friends, the devices they use and the social media platforms keep evolving. While Facebook remains the largest US teen social media network in 2015, it’s no longer the cool place to be. To reach US teens, you need a diversified social media strategy to maximize your potential audience. Based on Everybody Writes: Your Go-To Guide to Creating Ridiculously Good Content by Ann Handley. Subscribe to receive notice of each new actionable marketing post delivered free, directly to your inbox.
Tags Chart, Facebook, google+, Instagram, Mobile, Pew Research Center, SnapChat, teens, TUmblr, Twitter, Vine.
Couldn't make it to Social Media Marketing World 2016?Get all the sessions with the SMMW16 Virtual Pass. The Actionable Marketing Guide participates in the following affiliate marketing programs to bring you great products and services. While Ptolemy is most frequently associated with geography and cartography, he also wrote important works in a number of other fields including astronomy, astrology, music and optics. Although no original manuscript of this text has survived the ravages of time, several manuscript copies, dating from the closing centuries of the Byzantine Empire (ca. For these and other reasons, Ptolemy knew mathematics to be an important part of cartography. The first Book of the Geographia is devoted primarily to theoretical principles, including a discussion of globe construction, the description of two map projections, and an extended, through amicable, criticism of his primary source, Marinus of Tyre, a€?the latest of the geographers of our timea€?.
In another chapter in Book I, Ptolemy wrote that there are two ways of making a portrait of the world: one is to reproduce it on a sphere, and the other is to draw it on a plane surface.
If the second method of drawing the earth is used, that is, if the spherical earth is projected onto a plane surface, certain adjustments are obviously necessary. Ptolemya€™s exhaustive criticism of the imperfect methods of drawing maps adopted by Marinus would lead to the expectation that he himself would have used some of his own recommended projections in constructing his maps. Book II of the Geographia opens with a prologue a€?of the particular descriptionsa€?, which is to say, the maps he was about to present, and a general statement of his mapmaking policy. The fifth chapter of Book VII contains a description of the map of the world, together with an enumeration of the oceans and of the more important bays and islands.
In the eighth and last Book of the Geographia, Ptolemy returned to the business of discussing the principles of cartography, mathematical, geographical and astronomical methods of observation, and, in some cases (manuscript or printed copies) there follow short legends for each of the special maps - ten for Europe, four for Africa and twelve for Asia - mentioning the countries laid down on each plate, describing the limits, and enumerating the tribes of each country and its most important towns.
Those scholars who have argued that Ptolemya€™s original text contained no maps have neglected careful study of this Book. The obvious way to avoid crowding, Ptolemy said, is to make separate maps of the most populous regions or sectional maps combining densely populated areas with countries containing few inhabitants, if such a combination is feasible. The illustration above gives a diagram of the parts of the known world embraced by each special map found in Ptolemya€™s Geographia.
While there is little doubt still lingering that Ptolemya€™s text was originally illustrated by maps, it is not altogether certain that the maps found today in existing copies of the Geographia are indeed similar to those of the original series of maps, since the latter have not survived for comparison. To further confound the issue, all of the other manuscript copies of the Geographia that are accompanied by maps differ one from another, presenting two basic versions. The other version, B, contains sixty-four maps distributed throughout the text, vice collected together in one place. Over and above these maps, those manuscripts with maps, both A- and B-versions, are additionally illustrated with a universal map of the entire known world at Ptolemya€™s time, either on one sheet or four sheets; only very rarely are both world maps found together. As with modern maps, Ptolemaic maps are oriented so that North would be at the top and East at the right, because better known localities of the world were to be found in the northern latitudes, and on a flat map they would be easier to study if they were in the upper right-had corner. Displayed on the left-had margin of these world maps are seven Clima [Klima] and Parallel Zones.
Overall Ptolemya€™s world-picture extended northward from the equator a distance of 31,500 stades [one mile = 9 to 10 stades; there has always been some controversy over the equivalent modern length of a stade] to 63A° N at Thule, and southward to a part of Ethiopia named Agysimba and Cape Prasum at 16A° S latitude, or the same distance south as Meroe was north.
It has been repeatedly pointed out that the distances set down by Ptolemy in his tables for the Mediterranean countries, the virtual center of the habitable world, are erroneous beyond reason, considering the fact that Roman Itineraries were accessible. The geographical errors made by Ptolemy in his text and maps constitute the principle topic of many scholarly dissertations. Paradoxically, Ptolemya€™s eastward extension of Asia, reducing the length of the unknown part of the world, coupled with his estimate of the circumference of the earth, was his greatest contribution to history if not cartography. Ptolemy provides a descriptive summary in his text in which he tells us that the habitable part of the earth is bounded on the south by the unknown land which encloses the Indian Sea and that it encompasses Ethiopia south of Libya, called Agisymba. The southern limit of the habitable world had been fixed by Eratosthenes (#112) and Strabo (#115) at the parallel through the eastern extremity of Africa, Cape Guardafiri, the cinnamon-producing country and the country of the SembritA¦ [Senaai]. Ptolemy records, following Marinus, the penetration of Roman expeditions to the land of the Ethiopians and to Agisymba, a region of the Sudan beyond the Sahara desert, perhaps the basin of Lake Chad, and he supplied other new information regarding the interior of North Africa.
The eastern coast of Africa was better known than the western, having been visited by Greek and Roman traders as far as Rhapta [Rhaptum Promontory opposite Zanzibar?] which Ptolemy placed at about 7A° S. According to Greek tradition, an extension of 20A° in the width of the habitable world called for a proportionate increase in its length. Ptolemya€™s knowledge of the vast region from Sarmatia to China was, however, better than that of previous map makers. Many faults appear in Ptolemya€™s picture of southern Asia, although for more than a century commercial relations between western India and Alexandria had been flourishing. Even the more familiar territory of the Mediterranean basin demonstrated that insufficient contemporary knowledge was available and Ptolemy erred in many important cartographical details.
Map on grid system, in Ptolemy, La geographia, 1561-64, 26 x 14 cm, a€?Oxford University Byw. However, Ptolemy was apparently the first of the ancient geographers to have a fair conception of the relations between the Tanais, usually considered the northern boundary between Europe and Asia, and the Rha [Volga], which he said flowed into the Caspian Sea. In spite of the egregious errors on all of Ptolemya€™s maps, his atlas was indeed an unsurpassed masterpiece for almost 1,500 years.
During the intellectual narrow-mindedness of the Middle Ages even Ptolemy and his methods of map construction were forgotten, at least in the west. The presently known version of Ptolemya€™s works began to surface when the Byzantine monk Maximos Planudes (1260 - 1310) succeeded in finding and purchasing a manuscript copy of the Geographia.
Another scholar of the Byzantine age is known to have been interested in Ptolemya€™s Geographia - the noted polyhistor Nikephoras Gregoras (1295 - c. In 1400 a Greek manuscript copy of the A-version (twenty-six maps) was obtained from Constantinople by the Florentine patron of letters, Palla Strozzi, who persuaded Emmanual Chrysoloras, a Byzantine scholar, to translate the text into Latin. Again, the original manuscript of Angelusa€™ translation and the first maps of Ptolemy in the Latin language have not survived, but a manuscript copy, dated 1427, prepared under the direction of Cardinal Fillastre, can be found in the library at Nancy, France (thus known as the Nancy Codex). In manuscript form, four other cartographers are significant in editing and influencing the evolution of Ptolemya€™s atlas.
After the discovery of copper-plate and wood-engraving, Ptolemya€™s atlas became one of the first great works for the reproduction of which these arts were employed.
Some of these monographs may be thought of as an anthology of maps, which, like all anthologies, reflects the taste and predilection of the collector. Cartography, like architecture, has attributes of both a scientific and an artistic pursuit, a dichotomy that is certainly not satisfactorily reconciled in all presentations. The significance of maps - and much of their meaning in the past - derives from the fact that people make them to tell other people about the places or space they have experienced.
It is assumed that cartography, like art, pre-dates writing; like pictures, map symbols are apt to be more universally understood than verbal or written ones.
As previously mentioned, many early maps, especially those prior to the advent of mass production printing techniques, are known only through descriptions or references in the literature (having either perished or disappeared).
Many libraries and collections were not in the habit of preserving maps that they considered a€?obsoletea€? and simply discarded them. A series of maps of one region, arranged in chronological order, can show vividly how it was discovered, explored by travelers and described in detail; this may be seen in facsimile atlases like those of America (K. As mediators between an inner mental world and an outer physical world, maps are fundamental tools helping the human mind make sense of its universe at various scales. The history of cartography represents more than a technical and practical history of the artifacts. The only evidence we have for the mapmaking inclinations and talents of the inhabitants of Europe and adjacent parts of the Middle East and North Africa during the prehistoric period is the markings and designs on relatively indestructible materials. Although some questions will always remain unanswered, there can be no doubt that prehistoric rock and mobiliary art as a whole constitutes a major testimony of early mana€™s expression of himself and his world view. Despite the richness of civilization in ancient Babylonia and the recovery of whole archives and libraries, a mere handful of Babylonian maps have so far been found. Egypt, which exercised so strong an influence on the ancient civilizations of southeast Europe and the Near East, has left us no more numerous cartographic documents than her neighbor Babylonia. In so far as cartography was concerned, perhaps the greatest extant Egyptian achievement is represented by the Turin Papyrus, collected by Bernardino Drovetti before 1824 (see monograph #102) .
In so far as cartography was concerned, perhaps the greatest extent that Egyptian achievement is represented is by the Turin Papyrus, collected by Bernardino Drovetti before 1824 (#102).
It has often been remarked that the Greek contribution to cartography lay in the speculative and theoretical realms rather than in the practical realm, and nowhere is this truer than in the Archaic and Classical Period. To the Arab countries belongs chief credit for keeping alive an interest in astronomical studies during the so-called Christian middle ages, and we find them interested in globe construction, that is, in celestial globe construction; so far as we have knowledge, it seems doubtful that they undertook the construction of terrestrial globes.
Among the Christian peoples of Europe in this same period there was not wanting an interest in both geography and astronomy.
Above the convex surface of the earth (ki-a) spread the sky (ana), itself divided into two regions - the highest heaven or firmament, which, with the fixed stars immovably attached to it, revolved, as round an axis or pivot, around an immensely high mountain, which joined it to the earth as a pillar, and was situated somewhere in the far North-East, some say North, and the lower heaven, where the planets - a sort of resplendent animals, seven in number, of beneficent nature - wandered forever on their appointed path.
Now, it is remarkable that the Greeks, adopting the earlier Chaldean ideas concerning the sphericity of the earth, believed also in the circumfluent ocean; but they appear to have removed its position from latitudes encircling the Arctic regions to a latitude in close proximity to the equator.
Notwithstanding this encroachment of the external ocean - encroachment which may have obliterated indications of a certain northern portion of Australia, and which certainly filled those regions with the great earth - surrounding river Okeanos - the traditions relating to the existence of an island, of immense extent, beyond the known world, were kept up, for they pervade the writings of many of the authors of antiquity.
In a fragment of the works of Theopompus, preserved by Aelian, is the account of a conversation between Silenus and Midas, King of Phrygia, in which the former says that Europe, Asia, and Africa were lands surrounded by the sea; but that beyond this known world was another island, of immense extent, of which he gives a description.
Theopompus declareth that Midas, the Phrygian, and Selenus were knit in familiaritie and acquaintance.
The side of the boat curves inwards, so that when reversed the figure of it would be like an orange with a slice taken off the top, and then set on its flat side.
Comparing these early notions, as to the shape and extent of the habitable world, with the later ideas which limited the habitable portion of the globe to the equatorial regions, we may surmise how it came to pass that islands--to say nothing of continents which could not be represented for want of space - belonging to the southern hemisphere were set down as belonging to the northern hemisphere. We have no positive proof of this having been done at a very early period, as the earlier globes and maps have all disappeared; but we may safely conjecture as much, judging from copies that have been handed down. Early maps of the world, as distinguished from globes, take us back to a somewhat more remote period; they all bear most of the disproportions of the Ptolemaic geography, for none belonging to the pre-Ptolemaic period are known to exist. We have seen that, according to the earliest geographical notions, the habitable world was represented as having the shape of an inverted round boat, with a broad river or ocean flowing all round its rim, beyond which opened out the Abyss or bottomless pit, which was beneath the habitable crust.
The description is sufficiently clear, and there is no mistaking its general sense, the only point that needs elucidation being that which refers to the position of the earth or globe as viewed by the spectator. Our modern notions and our way of looking at a terrestrial globe or map with the north at the top, would lead us to conclude that the abyss or bottomless pit of the inverted Chaldean boat, the Hades and Tartaros of the Greek conception, should be situated to the south, somewhere in the Antarctic regions.
The internal evidence of the Poems points to a northern as well as a southern location for the entrance to the infernal regions. Another probable source of information: The Phoinikes of Homer are the same Phoenicians who as pilots of King Solomona€™s fleets brought gold and silver, ivory, apes and peacocks from Asia beyond the Ganges and the East Indian islands.
European mariners and geographers of the Homeric period considered the bearing of land and sea only in connection with the rising and setting of the sun and with the four winds Boreas, Euros, Notos, and Sephuros. These mariners and geographers adopted the plan - an arbitrary one - of considering the earth as having the north above and the south below, and, after globes or maps had been constructed with the north at the top, and this method had been handed down to us, we took for granted that it had obtained universally and in all times. Such has not been the case, for the earliest navigators, the Phoenicians, the Arabs, the Chinese, and perhaps all Asiatic nations, considered the south to be above and the north below.
It is strange that some historians, in pointing out so cleverly that the Chaldean conception was more in accordance with the true doctrine concerning the form of the globe than had been suspected, fails, at the same time, to notice that Homer in his brain-map reversed the Chaldean terrestrial globe and placed the north at the top. During the middle ages, we shall see a reversion take place, and the terrestrial paradise and heavenly paradise placed according to the earlier Chaldean notions; and on maps of this epoch, encircling the known world from the North Pole to the equator, flows the antic Ocean, which in days of yore encircled the infernal regions.
At a later period, during which planispheric maps, showing one hemisphere of the world, may have been constructed, the circumfluent ocean must have encircled the world as represented by the geographical exponents of the time being; albeit in a totally different way than expressed in the Shumiro-Accadian records. It follows from all this that, as mariners did actually traverse those regions and penetrate south of the equator, the islands they visited most, such as Java, its eastern prolongation of islands, Sumbawa, etc., were believed to be in the northern hemisphere, and were consequently placed there by geographers, as the earliest maps of the various editions of Ptolemya€™s Geography bear witness. These mistakes were the result doubtless of an erroneous interpretation of information received; and the most likely period during which cognizance of these islands was obtained was when Alexandria was the center of the Eastern and Western commerce of the world. But to return to the earlier Pre-Ptolemaic period and to form an idea of the chances of information which the traffic carried on in the Indian Ocean may have offered to the Greeks and Romans, here is what Antonio Galvano, Governor of Ternate says in 1555, quoting Strabo and Pliny (Strabo, lib.
Now as the above articles of commerce, mentioned by Strabo and Pliny, after leaving their original ports in Asia and Austral-Asia, were conveyed from one island to another, any information, when sought for, concerning the location of the islands from which the spices came, must necessarily have been of a very unreliable character, for the different islands at which any stay was made were invariably confounded with those from which the spices originally came. From these facts, and many others, such as the positions given to the Mountain of the East or North-East of the Shumiro-Accads, the Mountain of the South, or Southwest, of Homer, and the Infernal Regions, we may conclude that the North Pole of the Ancients was situated somewhere in the neighborhood of the Sea of Okhotsk. It is in the Classical Period of Greek cartography that we can start to trace a continuous tradition of theoretical concepts about the size and shape of the earth. Likewise, it should be emphasized that the vast majority of our knowledge about Greek cartography in this early period is known primarily only from second- or third-hand accounts.
There is no complete break between the development of cartography in Classical and in Hellenistic Greece. In spite of these speculations, however, Greek cartography might have remained largely the province of philosophy had it not been for a vigorous and parallel growth of empirical knowledge.
That such a change should occur is due both to political and military factors and to cultural developments within Greek society as a whole. The librarians not only brought together existing texts, they corrected them for publication, listed them in descriptive catalogs, and tried to keep them up to date. The other great factor underlying the increasing realism of maps of the inhabited world in the Hellenistic Period was the expansion of the Greek world through conquest and discovery, with a consequent acquisition of new geographical knowledge. Among the contemporaries of Alexander was Pytheas, a navigator and astronomer from Massalia [Marseilles], who as a private citizen embarked upon an exploration of the oceanic coasts of Western Europe. As exemplified by the journeys of Alexander and Pytheas, the combination of theoretical knowledge with direct observation and the fruits of extensive travel gradually provided new data for the compilation of world maps. The importance of the Hellenistic Period in the history of ancient world cartography, however, has been clearly established. In the history of geographical (or terrestrial) mapping, the great practical step forward during this period was to locate the inhabited world exactly on the terrestrial globe. Thus it was at various scales of mapping, from the purely local to the representation of the cosmos, that the Greeks of the Hellenistic Period enhanced and then disseminated a knowledge of maps. The Roman Republic offers a good case for continuing to treat the Greek contribution to mapping as a separate strand in the history of classical cartography. The remarkable influence of Ptolemy on the development of European, Arabic, and ultimately world cartography can hardly be denied. Notwithstanding his immense importance in the study of the history of cartography, Ptolemy remains in many respects a complicated figure to assess. Still the culmination of Greek cartographic thought is seen in the work of Claudius Ptolemy, who worked within the framework of the early Roman Empire.
When we turn to Roman cartography, it has been shown that by the end of the Augustan era many of its essential characteristics were already in existence.
In the course of the early empire large-scale maps were harnessed to a number of clearly defined aspects of everyday life. Maps in the period of the decline of the empire and its sequel in the Byzantine civilization were of course greatly influenced by Christianity. Continuity between the classical period and succeeding ages was interrupted, and there was disruption of the old way of life with its technological achievements, which also involved mapmaking. The Byzantine Empire, though providing essential links in the chain, remains something of an enigma for the history of the long-term transmission of cartographic knowledge from the ancient to the modern world.
It may be necessary to emphasize that the ancient Greek maps shown in this volume are a€?reconstructionsa€? by modern scholars based upon the textual descriptions of the general outline of the geographical systems formed by each of the successive Greek writers so far as it is possible to extract these from their writings alone. China is Asiaa€™s oldest civilization, and the center from which cultural disciplines spread to the rest of the continent. An ancient wooden map discovered by Chinese archaeologists in northwest China's Gansu Province has been confirmed as the country's oldest one at an age of more than 2,200. The map of Guixian was unearthed from tombs of the Qin Kingdom at Fangmatan in Tianshui City of Gansu Province in 1986 and was listed as a national treasure in 1994.
Unlike modern maps, place names on these maps were written within big or small square frames, while the names of rivers, roads, major mountains, water systems and forested areas were marked directly with Chinese characters. Whoever sets out to write on the history of geography in China faces a quandary, however, for while it is indispensable to give the reader some appreciation of the immense mass of literature which Chinese scholars have produced on the subject, it is necessary to avoid the tedium of listing names of authors and books, some of which indeed have long been lost. As for the ideas about the shape of the earth current in ancient Chinese thought, the prevailing belief was that the heavens were round and the earth square. The following attempts to compare rather carefully the parallel march of scientific geography in the West and in China. A few weeks before the beginning of each new school year my heart beats a little faster and the excitement builds.
In this web page we provide detailed (e,2e) studies of electron impact ionization of noble gases including helium, neon, argon, krypton and xenon from near threshold to intermediate energies, where the outgoing electrons carry equal energy from the interaction. The experiments were conducted in the perpendicular plane, where the outgoing electrons are detected orthogonal to the incident electron beam. The data show the cross sections undergo complex variations as a function of incident energy, and in particular ionization of the heaviest target is at variance to all others that have been studied here.
The (e,2e) process provides the most precise experimental data for the study of the ionization of atomic and molecular targets by electron impact. By determining the momenta of the scattered and ejected electrons in a time correlated coincidence measurement, the differential ionization cross section (DCS) is derived for comparison with theoretical models.
Since the scattered and ejected electrons may emerge over a wide range of different angles, experiments usually define a specific scattering geometry in which to carry out the measurements. In the present work, we have constrained the spectrometer to measure the DCS only in the perpendicular geometry, where psi = 90A°.
For both electrons to emerge in this geometry it is necessary for an interaction with the target nucleus to occur, and this provides a stringent test of current ionization models. We have taken measurements with the incident electron energy E0 ranging from near the ionization threshold of the selected target, through to energies up to 80eV above the ionization potential (IP).
Understanding these processes is hence important in areas ranging from the production of plasmas in stellar and planetary atmospheres, through to electron impact ionization in lasers and in nuclear reactors.
In all cases results are presented for the outgoing electrons having equal energies at the analysers. The apparatus can measure the DCS from the coplanar to the perpendicular plane geometry by moving the electron gun, gas jet and Faraday cup together around the interaction region (figure 2).
The electron analysers consist of a 3-element electrostatic lens that focuses electrons from the interaction region into a hemispherical energy selector.
The data were taken over a period of several months, and the electron gun current was varied for each of the data sets so as to ensure linearity of the detection system. The energy of the incident electron beam was determined by observing the negative ion elastic scattering resonance in helium at ~19eV, so as to determine the offset in the gun due to contact potentials. The energies of the outgoing electrons were determined by observing inelastic scattering from the excited targets, and by considering the location of Fano resonances in the ionization continuum.
The experimental data for helium are taken from previous work carried out in Manchester re-presented here normalised to unity at the peak of the DCS to allow comparison with other noble gases. The ground state of helium is 1S0, with an electronic configuration 1s2, and so both bound electrons occupy s-shell orbitals prior to the interaction. For helium, neon and argon targets, the bound electrons occupy either s-orbitals or p-orbitals in their ground state. It was not possible to resolve these individual channels in our experiment (due to the limited energy resolution of the spectrometer) apart from for xenon, where results were taken for production of the different ion states at incident electron energies from 10eV to 30eV above the IP.
Figure 3 presents results for ionization of helium in the perpendicular plane for ten different incident energies ranging from 3eV to 80eV above the IP. As the incident electron energy increases, additional peaks are seen at angles around 90A° & 270A°. By 20eV above the IP three distinct peaks are clearly visible, the relative strength of the central peak to outer lobes decreasing monotonically as the energy increases. The physical reasons behind these structures has been described by several models, ranging from DWBA calculations through to TDCC models. There is only one process that can produce a peak at 180A? in the perpendicular plane without interaction with the target nucleus. The peaks at around 90A° & 270A° are found to result from elastic scattering of the incident electron from the core, followed by a single binary collision between the incident electron and a bound electron. It should be noted that although agreement between theory and experiment in the perpendicular plane has proven to be very good, the results in a coplanar geometry are not as satisfactory, particularly for non-equal outgoing electron energies. The results at the lowest energy are similar in shape to that for helium, with a single broad peak observed centred around 180A°. As the incident energy increases, the DCS for neon shows a very different character to that for helium. The mechanisms that produce these structures in neon must be quite different to that proposed for helium, apart from at the lowest energy where PCI is expected to dominate for all targets. Al-Hagan and co-workers recently considered the low energy regime for both He and H2 from threshold to ~10eV above threshold, and concluded that for these targets PCI dominates at energies <2eV, which is also consistent with the observations for neon presented here.
The results in figure 4 indicate that the interaction is clearly more complex, and may be due to the momentum distribution of the ionized p-electron and polarizability of the atom (which is 1.9 times greater for neon than for helium).
A similar study was carried out for argon, whose outer electronic structure ([Ne]3s23p6) is similar to neon ([He]2s22p6).
In the frozen-core approximation as used in many theories, the inner electrons are considered as spectators during the interaction, and so in this approximation the structure of the DCS should be similar for neon and argon. For argon, nine separate energies were chosen for study, so as to reveal the complex variation in the DCS as a function of energy. Once again the results for argon are not consistent with the simple models found successful for helium.
Figure 6 shows the results for krypton, which unlike helium, argon and neon also has bound electrons occupying the 3d-shell.
Once again results were taken for a lowest energy 2eV above the IP, with the data having much better statistical significance compared to those for argon at the same energy. As the energy increases, the results for krypton show a similar trend to that for argon, with the central minimum deepening until around 10eV above the IP where a central peak starts to emerge. The similarity between argon and krypton data tends to indicate that the d-shell electrons in the heavier target are not playing a significant role in the ionization process. As the heaviest isotopically stable noble gas target, xenon has the largest calculated size (108 pm) due to full occupation of the 4d, 5s and 5p shells.
The ionic ground states of Xe+ are sufficiently separated that it was possible to resolve ionization to individual states during the experiments, for energies up to 30eV above the IP. The data are particularly surprising since they do not follow the general trend seen for all other noble gas targets at higher energies. The minimum at 180A° is significantly deeper than for krypton under the same outgoing energy conditions, and unlike krypton this minimum then becomes shallower as the incident energy increases. These results show that the mechanism for ionization of xenon must once again be different to all other targets that have been studied.
As far as we are aware this phenomenon has never been observed for any other target, and it remains to be seen why this should occur for xenon. Only three energies were selected for these experiments, due to the difficulty of obtaining good statistical data. The set of data presented here for isotopically stable noble gases shows there is a large variation in the probability of ionization in the perpendicular plane.
The perpendicular plane is particularly poignant for testing the most sophisticated electron impact ionization models, since multiple scattering must occur for electrons to emerge in this plane.
The perpendicular plane has proven to be a fertile ground to test recent theoretical models, which have found success for simple targets such as helium and molecular hydrogen. It appears that PCI plays a role at the lowest measured energy for each target, although the significance of this process reduces as the target weight increases. The most surprising result is for the heaviest target xenon, since the relative magnitude of the central peak continues to increase as the incident energy increases, and the side lobes reduce to insignificance. It is worth noting that the resolved data for ionization to the different Xe+ states indicate there is little variation to the measured cross section due to fine structure effects. KLN thanks the Royal Society for an International Newton Research Fellowship held at the University of Manchester. Even if your audience doesn’t currently use these devices and social media platforms, they’ll gradually adapt them to keep up with their children.
Broken out by race, 85% of African-American teens own a smartphone, while 71% of white teens and 71% of Hispanic teens own a smartphone.
47% of AfricanAmerican teens who own cell phones, 46% of Hispanic teens who own cell phones, and 24% of white teens who own cell phones use messaging apps to send texts.
This is consistent with girls and women being known for communicating more than their male counterparts. Their social media use extends their communications and enables them to provide increased information using images and video.Here’s a full analysis of US adult social media 2015 usage. Like US adults, this number of friends is roughly the Dunbar number, the number of close relationships a person can maintain. In theory, these photos and videos are automatically deleted within a predetermined amount of time. I've just returned from San Diego where I presented a workshop session on Blogging at Social Media Marketing World 2016.
He composed a Table of Reigns, a chronological list of Assyrian, Persian, Greek, and Roman sovereigns dating from Nabonasar to Antoninus Pius, a biographical history of kingship.
He was interested in the earth, all of it, not just the habitable part, and tried to fit it into a scheme of the universe where it belonged.
Marinus had given this matter considerable thought, rejecting all previously devised methods of obtaining congruity on a flat map; yet, according to Ptolemy he had finally selected the least satisfactory method of solving the problem.
There is also an introduction to data collection, evaluation, preparations for drawing, how and in what order to mark boundaries, and how to use the appended tables. When traveling overland it is usually necessary to diverge from a straight line course in order to avoid inevitable land-barriers; and at sea, where winds are changeable, the speed of a vessel varies considerably, making it difficult to estimate over-water distances with any degree of accuracy.
The Indian Ocean, which is assumed to be bordered on the south by an unknown continent, uniting southern Africa with eastern Asia, is stated to be the largest sea surrounded by land. It is these legends which, in some editions, have been placed on the reverse of the maps, and they appear to have been originally intended for that purpose. In Chapter Two Ptolemy said, a€?It remains for us to show how we set down all places, so that when we divide one map into several maps we may be able to accurately locate all of the well-known places through the employment of easily understood and exact measurements.a€? On the other hand, some scholars even go so far as to say that maps were already drawn before certain portions of the text was addressed, so that they could be used as models for the completion of other portions of the text.
For instance, in a single map embracing the entire earth, he said, there is a tendency to sacrifice proportion, that is, scale, in order to get everything on the map. If several regional maps are made to supplement the general world map, they need not a€?measure the same distance between the circlesa€?, that is, be drawn to the same scale, provided the correct relation between distance and direction is preserved.
It demonstrates how Ptolemya€™s world had been systematically divided into twenty-six regions, each of which is mapped on a separate sheet. The reason for this doubt lies in the question of authorship of the maps which accompany extant copies. According to map historian Leo Bagrow, one version, A, contains twenty-six large maps included in the eighth Book of the text, each folded in half and, on the back, having a statement of the region portrayed, its bounds and a list of principle towns. In some manuscripts of the B-version, and in those without maps, the texts from the backs of the maps are combined together in a special edition, divided into chapters numbered 3-28.
Of the Greek manuscripts of the Geographia, as a whole or in part, known today, eleven of the A-version and five of the B-version have maps.
The meridians are spaced from each other a€?the third part of an equinoctial hour, that is, through five of the divisions marked on the equatora€?.
In Ptolemya€™s time, the latitude, or distance from the equator, was generally astronomically calculated from the length of the longest and the shortest day.
The numbers on the right of the Clima give the number of hours in the longest day at different latitudes, increasing from 12 hours at the equator to 24 hours at the Arctic Circle.
The a€?breadtha€? of the habitable world according to Ptolemy then equates to 39,500 stades [3,950 miles].
The earth was only 18,000 miles around at the equator; Poseidonius had stated it, Strabo substantiated it, and Ptolemy perpetuated it on his maps.
Of these, the Indicum Mare [Indian Ocean] is the largest, Our Sea [the Mediterranean] is the next and the Hyrcanian [Caspian] is the smallest. This parallel also passed through Taprobane usually considered the southernmost part of Asia. As to the source of the Nile, both Greeks and Romans had tried to locate it, but without success. Ptolemy extended the west coast of Africa with a free hand, and even though he reduced the bulge made by Marinus more than half, it was still way out of control. He shows, for the first time, a fairly clear idea of the great north-south dividing range of mountains of Central Asia, which he called Imaus, but he placed it nearly 40A° too far east and made it divide Scythia into two parts: Scythia Intra Imaum and Scythia Extra Imaum Montem [Within Imaus and Beyond Imaus].
His Mediterranean is about 20A° too long, and even after correcting his lineal value of a degree it was still about 500 geographical miles too long. Ptolemy was also the first geographer, excepting Alexander the Great, to return to the correct view advanced by Herodotus and Aristotle, that the Caspian was an inland sea without communication with the ocean (the Christian medieval cartographers were a long time in returning to this representation of the Caspian). Its wealth of detail still constitutes one of the most important sources of information for the historian and student of ancient geography. Many of the legends and conventional signs that he used are still employed by cartographers with only slight modifications.
Ptolemya€™s works were, however, thriving and contributing valuable insight to knowledgeable Arabs and those having access and understanding of the Arab or Greek language (it was only in the Islamic states and in these languages that the works of the Alexandrian scientist were preserved (see monographs #212, #213, #214-17, lbn Said, al-lstakhri, Ibn Hauqal, al-Kashgari, etc. Very few scholars, let alone other literate persons in Western Europe were familiar with the Greek language at this time, therefore this translation was a great stimulus to a€?popularizinga€? Ptolemy. Curiously enough it was first printed at Vincenza in 1475 (the date printed of 1462 is in error) without maps! It may also be likened to a book of reproductions of works of art, in the sense that the illustrations, even with the accompanying commentary, cannot really do justice to the originals. A knowledge of maps and their contents is not automatic - it has to be learned; and it is important for educated people to know about maps even though they may not be called upon to make them.
Some maps are successful in their display of material but are scientifically barren, while in others an important message may be obscured because of the poverty of presentation.
Maps constitute a specialized graphic language, an instrument of communication that has influenced behavioral characteristics and the social life of humanity throughout history.
Maps produced by contemporary primitive peoples have been likened to so-called prehistoric maps. In earlier times these maps were considered to be ephemeral material, like newspapers and pamphlets, and large wall-maps received particularly careless treatment because they were difficult to store. When, in 1918, a mosaic floor was discovered in the ancient TransJordanian church of Madaba showing a map of Palestine, Syria and part of Egypt, a whole series of reproductions and treatises was published on the geography of Palestine at that time. Kretschner, 1892), Japan (P.Teleki, 1909), Madagascar (Gravier, 1896), Albania (Nopcsa, 1916), Spitzbergen (Wieder, 1919), the northwest of America (Wagner, 1937), and others.


Indeed, much of its universal appeal is that the simpler types of map can be read and interpreted with only a little training.
Crone remarked that a€?a map can be considered from several aspects, as a scientific report, a historical document, a research tool, and an object of art. It may also be viewed as an aspect of the history of human thought, so that while the study of the techniques that influence the medium of that thought is important, it also considers the social significance of cartographic innovation and the way maps have impinged on the many other facets of human history they touch. It is reasonable to expect some evidence in this art of the societya€™s spatial consciousness. There is, for example, clear evidence in the prehistoric art of Europe that maps - permanent graphic images epitomizing the spatial distribution of objects and events - were being made as early as the Upper Paleolithic. In Mesopotamia the invention by the Sumerians of cuneiform writing in the fourth millennium B.C. In the former field, among other things, they attained a remarkably close approximation for a?s2, namely 1.414213.
The courses of the Tigris and Euphrates rivers offered major routes to and from the north, and the northwest, and the Persian Gulf allowed contact by sea along the coasts of Arabia and east to India. Within this span of some three thousand years, the main achievements in Greek cartography took place from about the sixth century B.C. Stevenson, it is not easy to fix, with anything like a satisfactory measure of certainty, the beginning of globe construction; very naturally it was not until a spherical theory concerning the heavens and the earth had been accepted, and for this we are led back quite to Aristotle and beyond, back indeed to the Pythagoreans if not yet farther. We are now learning that those centuries were not entirely barren of a certain interest in sciences other than theological.
It has now been ascertained and demonstrated beyond doubt that the earliest ideas concerning the laws of the universe and the shape of the earth were, in many respects, more correct and clearer than those of a subsequent period.
Ragozin, says the Shumiro-Accads had formed a very elaborate and clever idea of what they supposed the world to be like; they imagined it to have the shape of an inverted round boat or bowl, the thickness of which would represent the mixture of land and water (ki-a) which we call the crust of the earth, while the hollow beneath this inhabitable crust was fancied as a bottomless pit or abyss (ge), in which dwelt many powers. The account of this conversation, which is too lengthy here to give in full, was written three centuries and a half before the Christian era. Of the familiaritie of Midas, the Phrigian, and Selenus, and of certaine circumstances which he incredibly reported. This Selenus was the sonne of a nymphe inferiour to the gods in condition and degree, but superiour to men concerning mortalytie and death. The Chaldean conception, thus rudely described, shows a yet nearer approximation to the true doctrine concerning the form of the globe, when we bear in mind that this actually is in shape a flattened sphere, with the vertical diameter the shorter one. A curious example of the difficulties that early cartographers of the circumfluent ocean period had to contend with, and of the sans faA§on method of dealing with them, occurs in the celebrated Fra Mauro mappamundi (Book III, #249), which is one of the last in which the external ocean is still retained. The influence of the Ptolemaic astronomical and geographical system was very great, and lasted for over thirteen hundred years. There are reasons to believe however, apart from the evidence we gather in the Poems, that these abyssal regions were supposed or believed to be situated around the North Pole.
Homer, The Outward Geography Eastwards: a€?The outer geography eastwards, or wonderland, has for its exterior boundary the great river Okeanos, a noble conception, in everlasting flux and reflux, roundabout the territory given to living man. The Phoenician reports referred to came most likely therefore, not so much from the north, as from these regions which, tradition tells us (Fra Mauroa€™s mappamundi #249), were situated propinqua ale tenebre. These winds covered the arcs intervening between our four cardinal points of the compass, which points were not located exactly as with us; but the north leaning to the east, the east to the south, the south to the west and the west to the north (see Beatusa€™ Turin map, Book II, #207). The reason for this is plausible, for whereas the northern seaman regulated his navigation by the North Star, the Asiatic sailor turned to southern constellations for his guidance. This is all the more strange when we take into consideration that, in the light of his context, the fact is apparent and of great importance as coinciding with other European views concerning the location of the north on terrestrial globes and maps.
The Chaldeans placed their heaven in the east or northeast; Homer placed his heaven in the south or southwest.
In this ocean we find also EA the Exalted Fish, but, deprived of his ancient grandeur and divinity, he is no doubt considered nothing more than a merman at the period when acquaintance is renewed with him on the SchA¶ner-Frankfort gores of Asiatic origin bearing the date 1515 (Book IV, #328). The divergence was probably owing in a great measure to the inability of representing graphically the perspective appearance of the globe on a plane; but may be also traceable to an erroneous interpretation of the original idea, caused by the reversion of the cardinal points of the compass.
According to this division other continents south of the equator were supposed to exist and habited, some said, but not to be approached by those inhabiting the northern hemisphere on account of the presumed impossibility of traversing the equatorial regions, the heat of which was believed to be too intense. We shall see, when dealing with Ptolemy's map of the world, some of the results of this confusion.
Thomas, after the dispersion of the Apostles, preached the Gospel to the Parthians and Persians; then went to India, where he gave up his life for Jesus Christ. That he corroborates Homera€™s views as to the sphericity of the earth by describing Cratesa€™ terrestrial globe (Geographica; Book ii. That he accentuates Homera€™s views concerning the black races that lived some in the west (the African race) others in the east (the Australian race). That he shows the four cardinal points of the compass to have been situated somewhat differently than with us, for he says (Book 1, c.
That he appears to be perpetuating an ancient tradition when he supposes the existence of a vast continent or antichthonos in the southern hemisphere to counterbalance the weight of the northern continents. The relativeness of these positions appears to have been maintained on some mediaeval maps.
To appreciate how this period laid the foundations for the developments of the ensuing Hellenistic Period, it is necessary to draw on a wide range of Greek writings containing references to maps. We have no original texts of Anaximander, Pythagoras, or Eratosthenes - all pillars of the development of Greek cartographic thought.
In contrast to many periods in the ancient and medieval world and despite the fragmentary artifacts, we are able to reconstruct throughout the Greek period, and indeed into the Roman, a continuum in cartographic thought and practice.
Indeed, one of the salient trends in the history of the Hellenistic Period of cartography was the growing tendency to relate theories and mathematical models to newly acquired facts about the world - especially those gathered in the course of Greek exploration or embodied in direct observations such as those recorded by Eratosthenes in his scientific measurement of the circumference of the earth.
With respect to the latter, we can see how Greek cartography started to be influenced by a new infrastructure for learning that had a profound effect on the growth of formalized knowledge in general. Thus Alexandria became a clearing-house for cartographic and geographical knowledge; it was a center where this could be codified and evaluated and where, we may assume, new maps as well as texts could be produced in parallel with the growth of empirical knowledge. In his treatise On the Ocean, Pytheas relates his journey and provides geographical and astronomical information about the countries that he observed.
While we can assume a priori that such a linkage was crucial to the development of Hellenistic cartography, again there is no hard evidence, as in so many other aspects of its history, that allows us to reconstruct the technical processes and physical qualities of the maps themselves. Its outstanding characteristic was the fruitful marriage of theoretical and empirical knowledge.
Eratosthenes was apparently the first to accomplish this, and his map was the earliest scientific attempt to give the different parts of the world represented on a plane surface approximately their true proportions. By so improving the mimesis or imitation of the world, founded on sound theoretical premises, they made other intellectual advances possible and helped to extend the Greek vision far beyond the Aegean. While there was a considerable blending and interdependence of Greek and Roman concepts and skills, the fundamental distinction between the often theoretical nature of the Greek contribution and the increasingly practical uses for maps devised by the Romans forms a familiar but satisfactory division for their respective cartographic influences.
The profound difference between the Roman and the Greek mind is illustrated with peculiar clarity in their maps. Through both the Mathematical Syntaxis (a treatise on mathematics and astronomy in thirteen books, also called the Almagest and the Geography (in eight books), it can be said that Ptolemy tended to dominate both astronomy and geography, and hence their cartographic manifestations, for over fourteen centuries.
A modern analysis of Ptolemaic scholarship offers nothing to revise the long-held consensus that he is a key figure in the long term development of scientific mapping. In its most obvious aspect, the exaggerated size of Jerusalem on the Madaba mosaic map (# 121) was no doubt an attempt to make the Holy City not only dominant but also more accurately depicted in this difficult medium. In both Western Europe and Byzantium relatively little that was new in cartography developed during the Dark Ages and early Middle Ages, although monks were assiduously copying out and preserving the written work of many past centuries available to them. Researcher He said that the map, drawn in black on four pine wood plates of almost the same size, had clear and complete graphics depicting the administrative division, a general picture of local geography and the economic situation in Guixian County in the Warring States era. Only a few examples can be given, but it should be understood, even when it is not expressly said, that they must often stand simply as representative of a whole class of works.
It may be said at the outset that both in East and West there seem to have been two separate traditions, one which we may call a€?scientific, or quantitative, cartographya€™, and one which we may call a€?religious, or symbolic, cosmographya€™. Some mothers are feeling guilt about not getting to every single thing all the way to the end.
We want our children to really learn what they are studying and gain skills for the future. As we journeyed through our home school years, I learned to lighten up and ask myself if my children were learning.
Since I learned a long time ago that putting stuff like this on paper gets it out of my worrying head, I like to schedule the whole year out ahead of time.
Each Sunday night or Monday morning, I look at our calendar and think about the different children, consider illness, my monthly cycle schedule, and other mitigating factors.
I re-study Proverbs 31, 1 Corinthians 13, and some of my favorite teaching passages from Mason, Montessori, and Suzuki. For electrons to emerge in this geometry they must undergo multiple scattering including scattering from the nucleus of the target, and so this provides a highly sensitive test for scattering theories. In these experiments a single electron of well defined momentum impacts with a target in the interaction region, resulting in target ionization and a scattered and ejected electron which emerge after the interaction has taken place. Our (e,2e) apparatus can access a wide range of geometries from a coplanar geometry, where the incident, scattered and ejected electrons all occupy the same plane, through to the perpendicular geometry, where the scattered and ejected electrons emerge in a plane orthogonal to the incident electron trajectory (figure 1). In this regime the probability of single ionization is a maximum, and so it is here that most ionizing collisions with electrons occur in nature. Low energy electron ionization has also been attributed to the production of DNA damage in biological tissue, and so it is important to understand these collisions at a fundamental level to describe the physics of these processes.
The helium results are reproduced from previous studies carried out in Manchester, re-presented here for completeness. By choosing the analyser residual energy to pass electrons around the selector, a channel electron multiplier detects electrons of the specified energy for subsequent amplification and counting.
In the perpendicular plane, only the mutual angle phi = xi1 + xi2 is relevant, where xi1, xi2 are as shown in figure 1.
The orbital angular momentum of each electron is hence zero, with a momentum distribution that peaks around zero a.u. The configuration of the 10 electrons in neon is 1s22s22p6, whereas argon has 18 electrons occupying a configuration [Ne]3s23p6. The data files for these results can be downloaded as a TAB deliminated text file Helium.txt. Experimental results for the ionization of helium in the perpendicular plane, with incident energies ranging from 3eV to 80eV above the ionization potential for this target.
This is considered to be due to the dominance of post-collisional interactions (PCI) between the outgoing electrons, which drives electrons emerging with equal energies from the interaction region asymptotically towards opposite directions.
At ~50eV excess energy the three lobes have equal amplitudes, whereas at higher energies the outer lobes dominate. The DWBA theory most easily allows the different processes involved in the interaction to be switched on and off, and this has explained the origin of these lobes. This process requires the momentum of the incident electron to be exactly matched by the momentum of the bound electron, with both electrons moving in opposite directions prior to the interaction.
In this case, since the particles have equal mass and energy, they emerge from the interaction region at a mutual angle of 90A° & 270A° as observed. It is therefore clear that further work is needed to fully describe the ionization reaction, even for a simple target like helium. The lowest energy studied was 5eV above the IP, with six measurements being taken up to 50eV above the IP as shown. Experimental results for the ionization of neon in the perpendicular plane, with incident energies ranging from 5eV to 50eV above the ionization potential for this target.
The width for this peak in neon is ~120A°, which is broader than ~80A° for the same outgoing electron energy in helium. As the energy is raised to 10eV above the IP, the broad single peak seen at the lowest energy increases in width, and develops a flat structure at the peak.
However, at higher energies the mechanisms proposed for helium ionization described above would be expected to produce similar structures in all targets that have a central ionic core. The calculated atomic radius of argon (71pm) is however significantly larger than that for helium (31pm) or neon (38pm) due to the n=3 shell being occupied. Experimental results for the ionization of argon in the perpendicular plane, with incident energies ranging from 2eV to 50eV above the ionization potential for this target.
The lowest energy studied was 2eV above the IP, the data at this energy having poor statistics due to experimental difficulties working with argon at this energy.
This minimum flattens at 10eV above the IP and rapidly evolves into a clear peak 15eV above the IP. The results further indicate that the use of a A”frozen-coreA• approximation is unlikely to be accurate in any theory attempting to emulate these data.
The physical size of krypton (88pm) is slightly larger than argon due to occupation of this shell, and due to closed occupation of the 4s and 4p shells. Experimental results for the ionization of krypton in the perpendicular plane, with incident energies ranging from 2eV to 50eV above the ionization potential for this target. Ionization of krypton no longer shows the dominance of PCI as predicted by Wannier, since there is now a central minimum at 180A°.
This central peak is not as significant in krypton compared to the side lobes, and by 30eV above the IP is once again diminishing. It also appears that the variation in cross section as a function of energy follows a similar pattern for each of these targets. A coincidence energy loss spectrum is shown in figure 7 to illustrate this separation at an incident electron energy 10eV above the IP for this target.
The results were taken from 2eV above the IP to 70eV above the IP for this target, so as to establish the variation in the cross section that is observed. At the lowest energy 2eV above the IP, a clear two-peak structure is observed which is similar to that observed from krypton. The results at higher energies are surprising, as the mechanism that produces the central peak with the electrons moving opposite each other is clearly dominating all other scattering processes. The data files for these results can be downloaded as a TAB deliminated text file Xenon2.txt.
These data indicate that fine structure in the final ion state does not play a significant role in the ionization process, since the comparison between this data and that reproduced from figure 8 shows that the shapes of the cross section for each energy are very similar. This contrasts to the coplanar geometry most often adopted, where the dominant scattering mechanism is usually a single binary scattering between electrons, resulting in a high probability that forward scattering occurs.
The results presented here will hence further test these models for heavier targets, so as to elucidate the scattering mechanisms that result in the observations. Argon, krypton and xenon also all evolve a central peak as the incident electron energy increases from near threshold, which cannot be due to PCI. The side lobes observed previously in the perpendicular plane have been attributed to a binary collision between the incident electron elastically scattered into this plane and a bound electron. It is hence likely that the results for neon, argon and krypton are also not significantly altered by these effects, even though the spectrometer was not capable of resolving their individual ion states. CK would like to thank the University of Manchester for providing a PhD scholarship while carrying out this work.
Marketers need to be accessible via mobile to reach this demographic or you’re invisible!
Other social media platforms and apps continue to gain traction and fragment US teen social media use. Little is known personally of this pivotal man aside from the general period during which he was active ca. His Analemma was mathematical description of a sphere projected on a plane, subsequently known as an a€?orthographic projection,a€? which greatly simplified the study of gnomonics. He was also interested in the relationships between the earth and the sun, the earth and the moon, in scientific cause and effect of climate; and above all, he was concerned with a scientifically accurate portrayal of the spherical earth in a convenient readable form. These Byzantine copies of the Geographia are comprised of eight a€?Booksa€? which Ptolemy introduces by supplying two very influential definitions - that of chorography and geography.
Marinus had laid out a grid of strait lines equidistant from one another for both his parallels of latitude and meridians of longitude.
Because while Ptolemy employs his conical projection in his first general world map, for the remaining twenty-six special regional maps he uses the rectangular projection of Marinus with due observance of the ratio between the longitude and latitude at the base of the map.
Books II-VI and the first four chapters of Book VII are devoted to a complete catalogue of some 8,000 inhabited localities laid down in the twenty-six special maps of the geography. Nevertheless Ptolemy concluded that the most reliable way of determining distances was by astronomical observation, and by no other method could one expect to fix positions accurately.
In addition, a description of a projection of the inhabited hemisphere on a plane, by which it could retain its circular outline, or globular aspect is also given.
The better known regions have many place-names, while the lesser known have few, and, unless the map is carefully drawn, it will have some crowded, illegible areas, and some where distances are unduly extended. Ptolemy repeated that it would be not too far from the truth if instead of circles we draw straight lines for meridians and parallels. Generally these sheets are of about the same size, but the scales vary according to the space required for the legends.
Did Ptolemy actually design and construct the maps himself, were they made by a draftsman working under his supervision, or were they added, perhaps as late as 1450, by an energetic editor who thought the text needed some graphic emendation? The geographical coordinates of these towns are given, not in degrees, but in time; the longitude is expressed in hours and minutes corresponding to the distance from the meridian of Alexandria (one hour = 15 degrees, one minute = 15 minutes of a degree), and the latitude is expressed in terms of the length of the longest day, in hours and minutes (the greater the distance from the equator, the longer the day in summer).
Some of the manuscripts without maps contain references to accompanying maps, since lost, and in others, spaces have been left for maps to be inserted. In other words, the total span of twelve hours, representing the length of the habitable world, was to be partitioned by a series of thirty-six meridians spaced five degrees apart at the equator and converging at the North Pole.
The earth was accordingly divided into a number of zones, parallel to the equator and within which these days had a certain length, for instance of 12 -13, or 15 -16 hours.
Ptolemy a€?correcteda€? this length to 180A° (9,000 miles), still 50A° (2,500 miles) too long, an error arising from using the Fortunate Islands as his prime meridian which he placed about seven degrees (350 miles) too far to the east. It is very unlikely, in view of the secrecy attached to all maps and surveys of the Roman Empire.
This a€?shorter distancea€? that a mariner would have to travel west from the shores of Spain in order to reach the rich trading centers of Asia may have contributed to Columbusa€™ belief, or that of his royal sponsors, that they could compete with their rival neighbors, Portugal, in the newly opened sea-trade with India by sailing west.
The Emperor Nero had sent an expedition into Upper Egypt, and it had penetrated as far as the White Nile, about 9A° N latitude. On the same approximate parallel he located the region called Agisymba, inhabited by Ethiopians and abounding in rhinoceri, supposedly discovered by Julius Maternus, a Roman general. A more obvious area to stretch the length of the world was in eastern Asia where there was every likelihood of additional territory yet unexplored. Asia and Africa are extended considerably to the east and south, far more so than on any previous maps, but not without cause. His Mare Nostrum, from Marseilles to the opposite point on the coast of Africa, is 11A° of latitude instead of the actual 6.5A°.
This is especially true in the study of the earliest tribes that encompassed the Roman Empire in the first century of the Christian era, who were at that time barbarians, but who later bore the burden of civilization in Europe. He originated the practice of orienting maps so that North is at the top and East to the right, a custom so universal today that many people are lost when they try to read a map oriented any other way.
Planudes constructed a map based upon the instructions found in Ptolemya€™s eight books and subsequently, through Athanasios, Patriarch of Alexandria, had a copy of the Geographia, with maps made for Emperor Andronicus III. He is also credited with the four-page world map found in some manuscripts, chiefly the B-version.
When Chrysoloras was unable to complete the translation, it was finished by one of his students, Jacobus Angelus of Scarparia, between 1406 and 1410. In all, seven editions were printed in the 15th century, of which six were provided with large maps in folio, and thirty-three in the following century (a selected list taken from Tooley accompanies this monograph). They have often served as memory banks for spatial data and as mnemonics in societies without the printed word and can speak across the barriers of ordinary language, constituting a common language used by men of different races and tongues to express the relationship of their society to a geographic environment. Certain carvings on bone and petroglyphs have been identified as prehistoric route maps, although according to a strict definition, they might not qualify as a€?mapsa€?. In the present work, reconstruction of maps no longer extant are used in place of originals or assumed originals. Since the maps were missing, he drew them himself from indications in the ancient text, and when the work was finished, he commemorated this too in verse.
The map answered many hitherto insoluble or disputed questions, for example the question as to where the Virgin Mary met the mother of John Baptist. A series of maps of a coastal region (for example, that of Holland or Friesland) or of river estuaries (the Po, Mississippi, Volga, or lower Yellow River) gives information on the rate of changes in outline and their causes.
Maps represent an excellent mirror of culture and civilizationa€?, but they are also more than a mere reflection: maps in their own right enter the historical process by means of reciprocally structured relationships. But when it comes to drawing up the balance sheet of evidence for prehistoric maps, we must admit that the evidence is tenuous and certainly inconclusive. The same evidence shows, too, that the quintessentially cartographic concept of representation in plan was already in use in that period. Our divisions into 60 and 360 for minutes, seconds and degrees are a direct inheritance from the Babylonians, who thought in these terms. The Pharaohs organized military campaigns, trade missions, and even purely geographical expeditions to explore various countries.
From earliest times much of the area covered by the annual Nile floods had, upon their retreat, to be re-surveyed in order to establish the exact boundaries of properties. We find allusions to celestial globes in the days of Eudoxus and Archimedes, to terrestrial globes in the days of Crates and Hipparchus. In Justiniana€™s day, or near it, one Leontius Mechanicus busied himself in Constantinople with globe construction, and we have left to us his brief descriptive reference to his work. But above all these, higher in rank and greater in power, is the Spirit (Zi) of heaven (ana), ZI-ANA, or, as often, simply ANA--Heaven. On this map of the world the islands of the Malay Archipelago follow the shores of Asia from Malacca to Japan. Even the Arabs, who, after the fall of the Roman Empire, developed the geographical knowledge of the world during the first period of the middle ages, adopted many of its errors.
Volcanoes were supposed to be the entrances to the infernal regions, and towards the southeast the whole region beyond the river Okeanos of Homer, from Java to Sumbawa and the Sea of Banda, was sufficiently studded with mighty peaks to warrant the idea they may have originated.
Many cartographers of the renascence, whose charts indeed we cannot read unless we reverse them, must have followed Asiatic cartographical methods, and this perhaps through copying local charts obtained in the countries visited by them.
Taprobana was the Greek corruption of the Tamravarna of Arabian, or even perhaps Phoenician, nomenclature; our modern Sumatra. Geographical science was on the eve of reaching its apogee with the Greeks, were it was doomed to retrograde with the decline of the Roman Empire.
John III, King of Portugal, ordered his remains to be sought for in a little ruined chapel that was over his tomb, outside Meliapur or Maliapor.
In some cases the authors of these texts are not normally thought of in the context of geographic or cartographic science, but nevertheless they reflect a widespread and often critical interest in such questions. In particular, there are relatively few surviving artifacts in the form of graphic representations that may be considered maps. Despite a continuing lack of surviving maps and original texts throughout the period - which continues to limit our understanding of the changing form and content of cartography - it can be shown that, by the perioda€™s end, a markedly different cartographic image of the inhabited world had emerged.
Of particular importance for the history of the map was the growth of Alexandria as a major center of learning, far surpassing in this respect the Macedonian court at Pella. Later geographers used the accounts of Alexandera€™s journeys extensively to make maps of Asia and to fill in the outline of the inhabited world. Not even the improved maps that resulted from these processes have survived, and the literary references to their existence (enabling a partial reconstruction of their content) can even in their entirety refer only to a tiny fraction of the number of maps once made and once in circulation. It has been demonstrated beyond doubt that the geometric study of the sphere, as expressed in theorems and physical models, had important practical applications and that its principles underlay the development both of mathematical geography and of scientific cartography as applied to celestial and terrestrial phenomena. On his map, moreover, one could have distinguished the geometric shapes of the countries, and one could have used the map as a tool to estimate the distances between places.
To Rome, Hellenistic Greece left a seminal cartographic heritage - one that, in the first instance at least, was barely challenged in the intellectual centers of Roman society. Certainly the political expansion of Rome, whose domination was rapidly extending over the Mediterranean, did not lead to an eclipse of Greek influence.
Such knowledge, relating to both terrestrial and celestial mapping, had been transmitted through a succession of well-defined master-pupil relationships, and the preservation of texts and three-dimensional models had been aided by the growth of libraries.
The Romans were indifferent to mathematical geography, with its system of latitudes and longitudes, its astronomical measurements, and its problem of projections.
Yet Ptolemy, as much through the accidental survival and transmission of his texts when so many others perished as through his comprehensive approach to mapping, does nevertheless stride like a colossus over the cartographic knowledge of the later Greco-Roman world and the Renaissance. Pilgrims from distant lands obviously needed itineraries like that starting at Bordeaux, giving fairly simple instructions.
When we come to consider the mapping of small areas in medieval western Europe, it will be shown that the Saint Gall monastery map is very reminiscent of the best Roman large-scale plans. Some maps, along with other illustrations, were transmitted by this process, but too few have survived to indicate the overall level of cartographic awareness in Byzantine society. Eighty-two places are marked with their respective names, locations of rivers, mountains and forested areas on the map. Experts said that graphics, symbols, scales, locations, longitude and latitude are key elements of a map. Thus in the Ta Tai Li Chi, Tseng Shen, replying to the questions of Shanchu Li, admits that it was very hard to see how, on the orthodox view, the four comers of the earth could be properly covered. If we are always dragging the children through every book on the list to satisfy an imaginary deadline or an imaginary dictator, will they see education as a chore that must be finished or an excellent thing to pursue? Once again if Mother is being a drill-sergeant instead of a firm, kind encourager, she may not be building the type of relationship with her child that she wants for the long run.
When I say this, I mean that we only need to answer to our own ideals or goals or what have you. Sure some days will not go as well as other days, but to spend our time re-making or second guessing our decisions again and again is a sure ticket to anxiety.
I wona€™t brag about the cool schoolrooms of my past, because quite frankly, our studying is just as successful at the dining room table, on the floor, or on the couch. Reminding me of my eternal and earthly goals, these resources serve to bring an element of peace to my anxious mind.
Hence it is possible to accumulate a full range of DCS measurements over all scattering angles using this spectrometer. The incident electron can move from the coplanar geometry (psi = 0A°) to the perpendicular plane (psi = 90A°), the outgoing electrons being measured in the detection plane. The shape of the DCS for a given energy and target is then of importance, for comparison with theory. This contrasts with the other noble gas targets whose levels are 1S0, but whose valence electrons occupy closed p-orbitals. By contrast, the bound electrons in both of the heavier targets also occupy d-orbitals, with a correspondingly more complex momentum distribution.
As the outgoing electron energy is lowered, the post collisional interaction time increases, resulting in an increased flux in the 180A° direction. At excess energies over 80eV above the IP the central lobe has virtually disappeared, leaving only the two outer lobes in the DCS. In this case, momentum conservation requires the outgoing electrons to move in opposite directions (180A°) in the perpendicular plane. The data files for these results can be downloaded as a TAB deliminated text file Neon.txt. At 15eV above the IP this flat structure has evolved into two peaks with 180A° now being a local minimum. The static polarization of argon is eight times larger than for helium, so scattering effects due to polarization of the target are expected to be significantly larger than for neon or helium.
The data files for these results can be downloaded as a TAB deliminated text file Argon.txt. This central peak is visible for incident energies up to 40eV above the IP, until at the highest energy (50eV above the IP) this has once again disappeared, the side peaks having also moved outwards compared to at the lower energies. The relative magnitude of this minimum compared to the peaks around 110A° & 250A° is however larger than for higher incident energies, so there is probably a contribution to the cross section at this angle due to PCI.
This central peak has virtually disappeared 40eV above the IP and there is no evidence of a peak 50eV above the IP.
It might hence be expected that the cross section for the heaviest target (xenon) would follow a similar trend to that of argon and krypton. The data are fitted to two Gaussians, showing that contamination from each ionic state is <10% when the spectrometer is set to each peak in the cross section. The data files for these results can be downloaded as a TAB deliminated text file Xenon1.txt. This indicates that PCI is once again not the dominant mechanism producing the cross section at this energy. The relative magnitude of this peak compared to the lobes at 110A° and 250A° then increases in magnitude as the energy increases, as with krypton and argon. This result indicates that fine structure does not appear to play a significant role in electron collision processes at these energies. The marked contrast between results for helium and all other noble gas targets demand that these models carefully consider the intricacies of the interaction, since a simple extension of the basic physical ideas presented for helium cannot explain the experimental data. For argon and krypton the relative magnitude of this peak increases with respect to the side lobes until it reaches a maximum, then decreases to become insignificant at the highest energies measured. This process has always been considered as the dominant mechanism at higher incident energies, yet the new results presented here indicate these ideas need to be revisited for this heavy target. His work entitled PlanisphA¦rium [the Planisphere], described a sphere projected on the equator, the eye being at the pole, a projection later known as a€?stereographica€?. More than any one of the ancients, Claudius Ptolemy succeeded in establishing the elements and form of scientific cartography. He defines chorography as being selective and regional in approach, a€?even dealing with the smallest conceivable localities, such as harbors, farms, villages, river courses, and the likea€?. Its position under the heavens is extremely important, for in order to describe any given part of the world one must know under what parallel of the celestial sphere it is located. He seems to have studied and made astronomical observations in Tyre, the oldest and largest city of Phoenicia, which, even at that late date, maintained important commercial relations with remote parts of the world. This was contrary to both truth and appearance, and the resulting map was badly distorted with respect to distance and direction, for if the eye is fixed on the center of the quadrant of the sphere which we take to be our inhabited world, it is readily seen that the meridians curve toward the North Pole and that the parallels, though they are equally spaced on the sphere, give the impression of being closer together near the poles. Traditional information regarding distances should be subordinated, especially the primitive sort, for tradition varies from time to time, and if it must enter into the making of maps at all, it is expedient to compare the records of the ancient past with newer records, a€?deciding what is credible and what is incrediblea€?. It is remarkable that such questions never seemed to have occurred to Ptolemy, as: What is there to be found beyond Serica and Sinarum Situs? Ptolemy himself never actually employed this manner of projection, which has since, through more or less modified, been preferred by geographers for maps representing one of the hemispheres. Some map makers have a tendency to exaggerate the size of Europe because it is most populous, and to contract the length of Asia because little is known about the eastern part of it. As for his own policy, he said, a€?in the separate maps we shall show the meridians themselves not inclined and curved but at an equal distance one from another, and since the termini of the circles of latitude and of longitude of the habitable earth, when calculated over great distances do not make any remarkable excesses, so neither is there any great difference in any of our mapsa€?.
As this diagram shows, each regional map would encompass, besides its own proper territory, some parts of the neighboring countries. Ptolemy does not state specifically in his text whether he personally made any maps, and proponents of the theory that Ptolemy made no maps for this Geographia base their case on the notation in two of the existing manuscript copies, that a cartographer named AgathodA¦mon of Alexandria was the author of the accompanying map(s). It is no less difficult, also, to determine when the maps of the two versions (A and B) were made. The meridians in the southern hemisphere are extended from the equator at the same angle as those above it, but instead of converging at the South Pole they terminated at the parallel 8A° 25a€™ below the equator. The concept of the division of the earth into zones began as early as the sixth century B.C. While Ptolemya€™s map is based upon the theory that the earth is round, it bares repeating that it is to his credit that he depicts only that half of its surface which was then known, with very little attempt to speculate on or a€?fill-ina€? the unknown parts with his imagination. More specifically, Ptolemya€™s knowledge concerning the fringes of the habitable world and civilization was broader than earlier writers, such as Strabo (#115), but in some respects it was a little confused.
With Thule as the northern limit of Ptolemya€™s habitable world, he thus extended the breadth of this world from less than 60A° (Eratosthenes and Strabo) to nearly 80A°.
The silk trade with China had produced rumors of vast regions east of the Pamir and Tian Shan, hitherto the Greek limits of Asia.
These distortions represented an actual extension of geographical knowledge and are doubtless based on exaggerated reports of distances traveled. 80) containing sailing directions from the Red Sea to the Indus and Malabar, indicated that the coast from Barygaza [Baroch] had a general southerly trend down to and far beyond Cape Korami [Comorin], and suggested a peninsula in southern India. While Ptolemy's map is based upon the theory that the earth is round, it bares repeating that it is to his credit that he depicts only that half of its surface which was then known, with very little attempt to speculate on or a€?fill-ina€? the unknown parts with his imagination.
To be sure, there are other geographical fragments, individual maps and charts, isolated examples of the best in Greek, Roman, and Arabic cartography, but Ptolemya€™s Geographia is the only extant geographical atlas which has come down to us from the ancients.
His map projections, the conical and modified spherical, as well as the orthographic and stereographic systems developed in the Almagest, are still in use. This particular copy has not been recovered, however another copy attributed to Planudes is preserved, in part, in the monastery of Vatopedi on Mount Athos.
It was also during this time, the 14th century, that the twenty-six maps of the A-version were divided up into sixty-four.
This oldest Latin translation of Ptolemya€™s Geographia (confusingly and arbitrarily titled Cosmographia by Angelus) was at first disseminated in numerous, often splendidly decorated manuscript copies. A re-issue of the preceding, but with a new title-page, an account of the New World by Marcus Beneventanus, and a new map of the world by Ruysch, Nova Tabula. The most important edition of Ptolemy, containing the 27 maps of the ancient world and 20 maps based on contemporary knowledge, under the superintendence of Martin WaldseemA?ller.


Maps, with the exception of Asia V, printed from the same blocks as 1522 edition, and like them almost unaltered copies on a reduced scale of the maps of the 1513 edition. This implies that throughout history maps have been more than just the sum of technical processes or the craftsmanship in their production and more than just a static image of their content frozen in time. The reconstructions of such maps appear in the correct chronology of the originals, irrespective of the date of the reconstruction.
After the fall of Byzantium in 1453, its conqueror, the Turkish Sultan Mohammed II, found in the library that he inherited from the Byzantine rulers a manuscript of Ptolemya€™s Geographia, which lacked the world-map, and he commissioned Georgios Aminutzes, a philosopher in his entourage, to draw up a world map based on Ptolemya€™s text. Comparison of travelersa€™ maps from various periods show the development and change of routes or road-building and allows us to draw conclusions of every kind about the development or decay of farms, villages and towns. They were artistic treasure-houses, being often decorated with fine miniatures portraying life and customs in distant lands, various types of ships, coats-of-arms, portraits of rulers, and so on.
The development of the map, whether it occurred in one place or at a number of independent hearths, was clearly a conceptual advance - an important increment to the technology of the intellect - that in some respects may be compared to the emergence of literacy or numeracy. The historian of cartography, looking for maps in the art of prehistoric Europe and its adjacent regions, is in exactly the same position as any other scholar seeking to interpret the content, functions, and meanings of that art. Moreover, there is sufficient evidence for the use of cartographic signs from at least the post-Paleolithic period. They are impressed on small clay tablets like those generally used by the Babylonians for cuneiform inscriptions of documents, a medium which must have limited the cartographera€™s scope. The survey was carried out, mostly in squares, by professional surveyors with knotted ropes. We find that the Greek geographer Strabo gives us quite a definite word concerning their value and their construction, and that Ptolemy is so definite in his references to them as to lead to a belief that globes were by no means uncommon instruments in his day, and that they were regarded of much value in the study of geography and astronomy, particularly of the latter science. With stress laid, during the many centuries succeeding, upon matters pertaining to the religious life, there naturally was less concern than there had been in the humanistic days of classical antiquity as to whether the earth is spherical in form, or flat like a circular disc, nor was it thought to matter much as to the form of the heavens.
Hyde Clarke has more than once pointed out in The Legend of the Atlantis of Plato, Royal Historical Society 1886, etc., that Australia must have been known in the most remote antiquity of the early history of civilization, at a time when the intercourse with America was still maintained.
Between the lower heaven and the surface of the earth is the atmospheric region, the realm of IM or MERMER, the Wind, where he drives the clouds, rouses the storms, and whence he pours down the rain, which is stored in the great reservoir of Ana, in the heavenly ocean. Then in a northeasterly direction Homera€™s great river Okeanos would flow along the shores of the Sandwich group, where the volcanic peak of Mt.
Aristotlea€™s writings, for example, provide a summary of the theoretical knowledge that underlay the construction of world maps by the end of the Greek Classical Period.
Our cartographic knowledge must, therefore, be gleaned largely from literary descriptions, often couched in poetic language and difficult to interpret. The ambition of Eratosthenes to draw a general map of the oikumene based on new discoveries was also partly inspired by Alexandera€™s exploration. In this case too, the generalizations drawn herein by various authorities (ancient and modern scholars, historians, geographers, and cartographers) are founded upon the chance survival of references made to maps by individual authors.
Yet this evidence should not be interpreted to suggest that the Greek contribution to cartography in the early Roman world was merely a passive recital of the substance of earlier advances. If land survey did play such an important part, then these plans, being based on centuriation requirements and therefore square or rectangular, may have influenced the shape of smaller-scale maps.
This is perhaps more remarkable in that his work was primarily instructional and theoretical, and it remains debatable if he bequeathed a set of images that could be automatically copied by an uninterrupted succession of manuscript illuminators. While almost certainly fewer maps were made than in the Greco-Roman Period, nevertheless the key concepts of mapping that had been developed in the classical world were preserved in the Byzantine Empire. What is more surprising is that the map marks the location of Wei Shui, now known as the Weihe River, and many canyons in the area. The map of Guixian County has all these elements except longitude and latitude, according to historians. But when there is no separate room, things can get to be quite a mess without some basic organization, habits, and rules.
So about a week before we intend to have our first official day of a€?school,a€? I begin getting everyone up 5 min. For the data presented here, the perpendicular plane was chosen, so only the mutual angle phi = xi1 + xi2 is relevant.
The combined coincidence energy resolution of the unselected energy electron gun and the two analysers is ~1eV. Krypton has 36 electrons and has a ground state configuration [Ar]3d104s24p6, while xenon has 54 electrons with a ground state configuration [Kr]4d105s25p6. This type of threshold behaviour was first predicted by Wannier and was later considered by Peterkop, Rau and others to explain results in this regime. This mechanism was considered as being the main reason for the peak at 180A° until the work of Madison and co-workers in 2009 showed the probability of this occurring was low. As the energy increases further, the peaks separate in angle, and the minimum at 180A° deepens. This angular shift of the side lobes is consistent with PCI playing a continuing role in the interaction, since as the energy increases the effects of PCI diminish, and the electrons move away from 180A° as is observed. The data files for these results can be downloaded as a TAB deliminated text file Krypton.txt. However, unlike krypton and argon whose central peak reaches a maximum and then decreases, the central peak in xenon continues to dominate the cross section as the energy rises.
Further, the frozen core approximation often adopted in these models which treat all non-ionized electrons as spectators does not appear valid for the heavier targets when compared to neon, even thought the outer valence electrons have the same p-type character. 90 to 168 (during the reigns of Hadrian and Antoninus Pius) and that he lived in, or near, Alexandria Egypt. This he did through his second great treatise, Geographike Syntaxis, called by him, a€?the geographical guide to the making of mapsa€?, and, in later centuries, shortened to simply Geographia, or (incorrectly) Cosmographia.
Geography, he said, differs from chorography in that it deals with a€?a representation in picture of the whole known world together with the phenomena that are contained thereina€?. Otherwise how can one determine the length of its days and nights, the stars which are fixed overhead, the stars which appear nightly over the horizon and the stars which never rise above the horizon at all. This a€?tutora€™ of Ptolemy had read nearly all of the historians before him and had corrected many of their errors (presumable errors relating to the location of places as contained in travelersa€™ itineraries). Ptolemy was well aware that it would be desirable to retain a semblance of spherical proportions on his flat map, but at the same time he decided to be practical about it. With one exception (an Italian translation by Berlinghieri), every editor of Ptolemya€™s Geographia has published, not the original maps, but a modification of them by Nicolaus Germanus (Donis), who, with praiseworthy exactness and without any further alterations, reproduced the originals, on a projection with rectilinear, equidistant parallels and meridians converging towards the poles.
It is an exception when geographical or descriptive remarks are added to this bare enumeration of names. Therefore if a geographer were obliged to fall back on the reports of travelers, he should exercise some discrimination in his choice of authorities.
What could be found to the north of Thule, or to the south of Agysimba and Cape Prasum: Where would you arrive if you sailed westward from the Fortunate Islands?
And some cartographers surround the earth on all sides with an ocean that, according to Ptolemy are a€?making a fallacious description, and an unfinished and foolish picturea€?. But, as is also usual in modern atlases, these neighboring areas of the map are only roughly sketched, while the principle area is shown in full detail. From these same manuscripts it is stated that a€?he drew them according to the instructions in the eight books of Claudius Ptolemya€?. Certain indications point to the Byzantine period, with the exception of AgathodA¦mona€™s single-sheet world map. And it is highly probable that Ptolemy the astronomer, who is usually discredited by later geographers because of his methods and the kinds of information he compiled, had no more standing among some of his influential contemporaries than he would today in the most approved geographical circles of the civilized world.
The only good reason for discussing a few of the glaring faults of the Geographia is that it was the canonical work on the subject for more than 1400 years.
In the northern regions, for example, he had been ill-advised with regard to Ireland, and positioned it further north than any part of Wales; likewise, Scotland was twisted around so that its length ran nearly east and west. Ptolemy stated that the Nile arose from two streams, the outlets of two lakes a little south of the equator, which was closer to the truth than any previous conception until the discovery of the Victoria and Albert Nyanza in modern times. All such information was of doubtful origin, and in laying down the coastline of Eastern Asia, Ptolemy ran the line roughly north and south.
Ptolemy, apparently following Marinus, ignored this document, or else never saw it because the shape of his India is unduly broadened and foreshortened. Leaving the habitable world from the Strait at the Pillars of Hercules to the Gulf of Issus, it passed through Caralis in Sardinia and Lilybaeum in Sicily (30A° 12a€™ and 37A° 50a€™ N). Ptolemy stated that the Nile arose from two streams, the outlets of two lakes a little south of the equator, which was closer to the truth than any previous conception, or any later one until the discovery of the Victoria and Albert Nyanza in modern times.
There is nothing in the literature to indicate that any other such systematic collection of maps was ever compiled, with the exception of the maps of Marinus, about which almost nothing is known, save what Ptolemy has mentioned. The listing of place-names, either in geographical or alphabetical order, with the latitude and longitude of each place to guide the search, is not so different from the modern system of letters and numerals employed to help the reader, a little convenience that is standard on modern maps and Ptolemaic in origin. Four new mapsa€”France, Italy, Spain and Palestinea€”being based on contemporary knowledge. The map of the world is the first to show contemporary discoveries, and the first map to bear the name of its engraver, Johannes Schnitzer de Armssheim.
The other 6 mapsa€”northern Europe, Spain, France, Poland, Italy and the Holy Landa€”are based on contemporary knowledge. Includes the Tabula Terra Nova, the first map specifically devoted to the delineation of the New World. Indeed, any history of maps is compounded by a complex series of interactions, involving their intent, their use and their purpose, as well as the process of their making.
All reconstructions are, to a greater or lesser degree, the product of the compiler and the technology of his times.
He knew it would be out of date, but that is precisely what he wanted - an ancient map; to perpetuate it, he also had a carpet woven from the drawing. Inferences have to be made about states of mind separated from the present not only by millennia but also - where ethnography is called into service to help illuminate the prehistoric evidence - by the geographical distance and different cultural contexts of other continents. Two of the basic map styles of the historical period, the picture map (perspective view) and the plan (ichnographic view), also have their prehistoric counterparts.
However, the measurement of circular and triangular plots was envisaged: advice on this, and plans, are given in the Rhind Mathematical Papyrus of ca. From Ptolemaic Egypt there is a rough rectangular plan of surveyed land accompanying the text of the Lille Papyrus I, now in Paris; also two from the estate of Apollonius, minister of Ptolemy II. There is, however, but one example known, which has come down to us from that ancient day, this a celestial globe, briefly described as the Farnese globe.
Yet there was no century, not even in those ages we happily are learning to call no longer a€?darka€?, that geography and astronomy were not studied and taught, and globes celestial as well as armillary spheres, if not terrestrial globes, were constructed. Here however he makes his hero confess that he is wholly out of his bearings, and cannot well say where the sun is to set or to rise (Od. Although these views were continued and developed to a certain extent by their successors, Strabo and Ptolemy, through the Roman period, and more or less entertained during the Middle Ages, they became obscured as time rolled on. The bones of the holy apostle were found, with some relics that were placed in a rich vase. Again, if we consider the Atlantic and North Pacific Oceans as devoid of the American Continent, and the Atlantic Ocean as stretching to the shores of Asia, as Strabo did, the parallel of Iberia (Spain) would have taken Columbusa€™ ships to the north of Japan--i.e. At the time when Alexander the Great set off to conquer and explore Asia and when Pytheas of Massalia was exploring northern Europe, therefore, the sum of geographic and cartographic knowledge in the Greek world was already considerable and was demonstrated in a variety of graphic and three-dimensional representations of the heavens and the earth. In addition, many other ancient texts alluding to maps are further distorted by being written centuries after the period they record; they too must be viewed with caution because they are similarly interpretative as well as descriptive. Eudoxus had already formulated the geocentric hypothesis in mathematical models; and he had also translated his concepts into celestial globes that may be regarded as anticipating the sphairopoiia [mechanical spheres]. And it was at Alexandria that this Ptolemy, son of Ptolemy I Soter, a companion of Alexander, had founded the library, soon to become famous through the Mediterranean world.
It seems, though, that having left Massalia, Pytheas put into Gades [Cadiz], then followed the coasts of Iberia [Spain] and France to Brittany, crossing to Cornwall and sailing north along the west coast of England and Scotland to the Orkney Islands. On the contrary, a principal characteristic of the new age was the extent to which it was openly critical of earlier attempts at mapping.
Disregarding the elaborate projections of the Greeks, they reverted to the old disk map of the Ionian geographers as being better adapted to their purposes. This shape was also one which suited the Roman habit of placing a large map on a wall of a temple or colonnade. 90-168), Greek and Roman influences in cartography had been fused to a considerable extent into one tradition. The Almagest, although translated into Latin by Gerard of Cremona in the 12th century, appears to have had little direct influence on the development of cartography. Ptolemya€™s principal legacy was thus to cartographic method, and both the Almagest and the Geography may be regarded as among the most influential works in cartographic history. However, the maps of Marinus and Ptolemy, one of the latter containing thousands of place-names, were at least partly known to Arabic geographers of the ninth to the 10th century. The most accomplished Byzantine map to survive, the mosaic at Madaba (#121), is clearly closer to the classical tradition than to maps of any subsequent period. He Shuangquan, a research fellow with the Gansu Provincial Archaeological Research Institute, has made an in-depth study of the map and confirmed its drawing time to be 239 B.C. It is better to learn a little bit of a variety of things really well than a whole lot of things in a vague sort of way. They proposed a triple scattering mechanism to describe this peak, where the incident electron first scatters elastically from the nucleus so as to enter the detection plane, followed by a binary inelastic collision with a bound electron, followed by elastic scattering of one of the electrons back from the nucleus. This trend continues up to the highest energy which was possible to measure (70eV above the IP), where the central peak is seen to be broad with a width ~100A°. It is hence likely that these assumptions will need to be relaxed to accurately model the data.
During the second century, Alexandria was not only the richest city in the world, with regard to learned institutions and treasures of scholarship, but also the wealthiest commercial place on the earth. This work is actually the first general atlas of the world to have survived, rather than a a€?Geographya€? with a long textual introduction to the subject of cartography. As he proceeds to elaborate his definition of geography, it becomes apparent that Ptolemy conceived that the primary function of geography was a€?mapmakinga€?, and that, to him, geography was synonymous with cartography.
He had, moreover, edited and revised his own geographic maps, of which at least two editions had been published before Ptolemy saw them. Finally, Ptolemy thought, about all one could do was to locate unfamiliar places as accurately as possible with reference to well-known places, in as much as it is advisable on a map of the entire world to assign a definite position to every known place, regardless of how little is known about it. The longitudes would be determined from the meridian of Alexandria, either at sunrise or sunset, calculating the difference in equinoctial hours between Alexandria and point two, whatever it might be. As mentioned earlier, the original text called for twenty-six regional or special maps, which in all extant manuscript copies bear a strong family resemblance and are laid down on the projection apparently used by Marinus in the form of isosceles trapezoids. However, this statement has never been dated and, confusingly, AgathodA¦mona€™s single-sheet world map employs a projection unlike any proposed by Ptolemya€™s text. But, again, when they were constructed - totally and faithfully copied from the originals, or constructed from Ptolemya€™s instructions but without benefit of original models - is significant in trying to determine the degree of similarity to their a€?prototypea€™ and the possibility of additions or corrections based upon more contemporary knowledge. Different from what is now accepted as the meaning, this word in ancient maps had a purely geographical, not a meteorological significance, although they also perceived that the climate of a region was somewhat related to its distance from the equator. Similarly he showed the length of the Mediterranean as 62A°, whereas, in reality it is only 42A°. Geographers of the 15th and 16th centuries relied on it so heavily, while ignoring the new discoveries of maritime explorers, that it actually exerted a powerful retarding influence on the progress of cartography. Instead of continuing it to the Land of the LinA¦ [seacoast of China] he curved it around to the east and south, forming a great bay, Sinus Magnus [roughly the Gulf of Siam]. Carthage is positioned 1A° 20a€™ south of the parallel of Rhodes; actually it is one degree north of it. Corrected and amended by a succession of editors, this version also formed the basis upon which all of the editions of the 15th century are built. The text is a metrical paraphrase by Francesco Berlinghieri, and is the first edition in Italian. The greatly increased number of a€?modern mapsa€? makes this in effect the first modern atlas.
Therefore, reconstructions are used here only to illustrate the general geographic concepts of the period in which the lost original map was made. It was said that as the Archangel Gabriel appeared to Zacharias in the holy of holies, Zacharias must have been High Priest and have lived in Jerusalem; John the Baptist would then have been born in Jerusalem. I have not been able to find any such evidence or artifacts of map making that originated in the South America or Australia. This is described in an inscription in the Temple of Der-el-Bahri where the ship used for this journey is delineated, but there is no map. It is of marble, and is thought by some to date from the time of Eudoxus, that is, three hundred years before the Christian era. The Venerable Bede, Pope Sylvester I, the Emperor Frederick II, and King Alfonso of Castile, not to name many others of perhaps lesser significance, displayed an interest in globes and making.
See the sketch below of an inverted Chaldean boat transformed into a terrestrial globe, which will give an idea of the possible appearance of early globes. Indeed, wherever we look round the margin of the circumfluent ocean for an appropriate entrance to Hades and Tartaros, we find it, whether in Japan, Iceland, the Azores, or Cape Verde Islands. Terrestrial maps and celestial globes were widely used as instruments of teaching and research. Despite what may appear to be reasonable continuity of some aspects of cartographic thought and practice, in this particular era scholars must extrapolate over large gaps to arrive at their conclusions. By the beginning of the Hellenistic Period there had been developed not only the various celestial globes, but also systems of concentric spheres, together with maps of the inhabited world that fostered a scientific curiosity about fundamental cartographic questions. The library not only accumulated the greatest collection of books available anywhere in the Hellenistic Period but, together with the museum, likewise founded by Ptolemy II, also constituted a meeting place for the scholars of three continents.
From there, some authors believe, he made an Arctic voyage to Thule [probably Iceland] after which he penetrated the Baltic. Intellectual life moved to more energetic centers such as Pergamum, Rhodes, and above all Rome, but this promoted the diffusion and development of Greek knowledge about maps rather than its extinction.
The main texts, whether surviving or whether lost and known only through later writers, were strongly revisionist in their line of argument, so that the historian of cartography has to isolate the substantial challenge to earlier theories and frequently their reformulation of new maps.
There is a case, accordingly, for treating them as a history of one already unified stream of thought and practice. With translation of the text of the Geography into Latin in the early 15th century, however, the influence of Ptolemy was to structure European cartography directly for over a century. It would be wrong to over emphasize, as so much of the topographical literature has tended to do, a catalog of Ptolemya€™s a€?errorsa€?: what is vital for the cartographic historian is that his texts were the carriers of the idea of celestial and terrestrial mapping long after the factual content of the coordinates had been made obsolete through new discoveries and exploration. Similarly, in the towns, although only the Forma Urbis Romae is known to us in detail, large-scale maps were recognized as practical tools recording the lines of public utilities such as aqueducts, displaying the size and shape of imperial and religious buildings, and indicating the layout of streets and private property.
But the transmission of Ptolemya€™s Geography to the West came about first through reconstruction by Byzantine scholars and only second through its translation into Latin (1406) and its diffusion in Florence and elsewhere. But as the dichotomy increased between the use of Greek in the East and Latin in the West, the particular role of Byzantine scholars in perpetuating Greek texts of cartographic interest becomes clearer. Forested areas marked on the map also tallies with the distribution of various plants and the natural environment in the area today. While perfect execution is part of our goal, we want to achieve it through calmness and kindness not worry and strife.
If you decide that 29 chapters of history instead of 32 is enough for your school year, so be it. Do we live in such a way that a son or a daughter may say, a€?I want to follow my dad,a€? or a€?I want to be like my mothera€??
This complex mechanism was found to emulate the cross section more closely compared to the single scattering process originally envisaged. As for all measurements in this study, the DCS must be zero for the electrons emerging at the same angle (0A°, 360A°), due to post collisional interactions between outgoing electrons of equal energy.
At all energies greater than 40eV above the IP, the outer peaks seen in all other targets have disappeared. It was a place where seafaring people and caravans from all parts of the known world would use to congregate, thereby providing the opportunity to collect knowledge of far away lands and seas. Here for the first time are documented the duties and responsibilities of the mapmaker, his limitations, and the nature of the materials he was to work with. The final drafts were nearly free from defects and his text, which we know of only through Ptolemy, was so reliable in Ptolemya€™s estimation that a€?it would seem to be enough for us to describe the earth on which we dwell from his commentaries alone, without other investigations.a€? According to Ptolemy, the most significant feature of the maps of Marinus was the growth of the habitable world and the changed attitude toward the uninhabited parts. When such a conical surface is extended on a plane, a network with circular parallels and rectilinear, converging meridians arise.
Unlike Marinus who listed longitude on one page and latitude on another, Ptolemy began the tradition of listing the positional coordinates together and in a usable system that was practical to follow.
Some of the other conspicuously modern conventions include the previously noted lack of ornamentation, his method of differentiating land and water, rivers and towns, by means of either hachures or different colors, and his use of a€?standardizeda€™ symbols all of which is accepted at first glance without a thought being given to the origin of the technique. This particular world map is usually found at the end of Book VII, preceded by three chapters containing some practical advice, a general description of all known areas of the world and the three principle seas (the Mediterranean, the Caspian and the Indian Ocean), with their bays and islands, and instructions for drawing a sphere and maps on a plane surface. It is noteworthy here to point out that, regardless of when these existing manuscript reproductions were made, they somehow escaped the pictorial fancies such as sketches of animals, monsters, savages, ships, kings, etc. The eastward extension of Asia is also exaggerated, measuring about 110A° from the coast of Syria to the outermost limits of China, instead of the true distance of about 85A°. The Geographia was both a keystone and a millstone, a pioneering effort that outlived its usefulness.
The northern coast of Germany beyond Denmark, Cimbrica Chersonese, is shown as the margin of the Northern Ocean, and running in a general east-west direction. Continuing it around to the south until it joined Terra Incognita at the southern limit of the habitable world, he made a lake of the Indicum Mare [Indian Ocean].
For the most part, the lands beyond the Ganges were not well known until a thousand years later when the brothers Polo first acquainted western Europe with the existence of a number of large islands in that part of the world. Byzantium is placed in the same latitude as Massilia, which made it more than two degrees north of its true position. It is also the only edition with maps printed on the original projection with equidistant parallels or meridians. No one person or area of study is capable of embracing the whole field; and cartographers, like workers in other activities, have become more and more specialized with the advantages and disadvantages which this inevitably brings. Nevertheless, reconstructions of maps which are known to have existed, and which have been made a long time after the missing originals, can be of great interest and utility to scholars.
It has been shown how these could have appealed to the imagination not only of an educated minority, for whom they sometimes became the subject of careful scholarly commentary, but also of a wider Greek public that was already learning to think about the world in a physical and social sense through the medium of maps. The relative smallness of the inhabited world, for example, later to be proved by Eratosthenes, had already been dimly envisaged.
The confirmation of the sources of tin (in the ancient Cassiterides or Tin Islands) and amber (in the Baltic) was of primary interest to him, together with new trade routes for these commodities.
Indeed, we can see how the conditions of Roman expansion positively favored the growth and applications of cartography in both a theoretical and a practical sense. The context shows that he must be talking about a map, since he makes the philosopher among his group start with Eratosthenesa€™ division of the world into North and South. Here, however, though such a unity existed, the discussion is focused primarily on the cartographic contributions of Ptolemy, writing in Greek within the institutions of Roman society. In the history of the transmission of cartographic ideas it is indeed his work, straddling the European Middle Ages, that provides the strongest link in the chain between the knowledge of mapping in the ancient and early modem worlds. Finally, the interpretation of modem scholars has progressively come down on the side of the opinion that Ptolemy or a contemporary probably did make at least some of the maps so clearly specified in his texts.
Some types of Roman maps had come to possess standard formats as well as regular scales and established conventions for depicting ground detail. In the case of the sea charts of the Mediterranean, it is still unresolved whether the earliest portolan [nautical] charts of the 13th century had a classical antecedent. Byzantine institutions, particularly as they developed in Constantinople, facilitated the flow of cartographic knowledge both to and from Western Europe and to the Arab world and beyond. Although we do not want to emulate the public schools or make excuses, we should remember a few examples from our old public school teachers. Unlike the book on the library shelf, the covers of which shield the contents, our lives cannot be closed. In spite of such scant personal knowledge, Claudius Ptolemya€™s writings have had a greater influence on cartography, and on geography in general, than that of any other single figure in history.
141), a composition dealing with astronomy and mathematics, more commonly known by its hybrid Greco-Arabic title, the Almagest, in which he lays down the foundation of trigonometry and sets forth his view of the universe. This single treatise remained the standard work on geographical theory throughout the Middle Ages, was not superseded as such with the 16th century, and constitutes one of the fundamental tenants of modern geodesy.
Cartography is not an artistic endeavor according to the Greek scholar, but should be concerned with the relation of distance and direction, and with the important features of the eartha€™s surface that can be indicated by plain lines and simple notations (enough to indicate general features and fix positions).
Marinus was a good man in Ptolemya€™s estimation but he lacked the critical eye and allowed himself to be led astray in his scientific investigations.
Lest the proportions of certain parts of the mapped territory should be too much deformed, only the northern or the southern hemispheres should be laid down on the same map by this projection, which is consequently inconvenient for maps embracing the whole earth.
This particular projection shown of the general map of the habitable world, the one believed to be employed by Ptolemy in his original general map, is laid down in the lazy mana€™s projection he talked about, the modified conic instead of the spherical projection that he recommended for a faithful delineation of the eartha€™s surface.
Many scholars ascribe these three chapters to AgathodA¦mon, as the descriptive text for his map.
As can be seen from these world maps, Ptolemy divided the northern hemisphere into twenty-one parallels, noted, again, in the margin of this maps. To judge, therefore, from the map, Ptolemy discarded both the older Greek belief that the earth was surrounded by water, and Herodotusa€™ description of the Phoeniciana€™s circumnavigation of Africa.
And there were no good maps of the East Indian Archipelago until after the Portuguese voyages to the Indies. This particular error threw the whole Euxine Pontus [Black Sea], whose general form and dimensions were fairly well known, too far north by the same amount, over 100 miles. The possibilities include those for which specific information is available to the compiler and those that are described or merely referred to in the literature. Some saw in the a€?hill countrya€™ Hebron, a place that had for a long time been a leading Levitical city, while others held that Juda was the Levitical city concerned. The fact that King Sargon of Akkad was making military expeditions westwards from about 2,330 B.C.
The whole northern region, of sea as he supposed it, from west to east, was known to him only by Phoenician reports. If a literal interpretation was followed, the cartographic image of the inhabited world, like that of the universe as a whole, was often misleading; it could create confusion or it could help establish and perpetuate false ideas.
It had been the subject of comment by Plato, while Aristotle had quoted a figure for the circumference of the earth from a€?the mathematiciansa€? at 400,000 stades; he does not explain how he arrived at this figure, which may have been Eudoxusa€™ estimate. It would appear from what is known about Pytheasa€™ journeys and interests that he may have undertaken his voyage to the northern seas partly in order to verify what geometry (or experiments with three dimensional models) have taught him. Not only had the known world been extended considerably through the Roman conquests - so that new empirical knowledge had to be adjusted to existing theories and maps - but Roman society offered a new educational market for the cartographic knowledge codified by the Greeks.
Ptolemy owed much to Roman sources of information and to the extension of geographical knowledge under this growing empire: yet he represents a culmination as well as a final synthesis of the scientific tradition in Greek cartography that has been highlighted in this introduction. Yet it is perhaps in the importance accorded the map as a permanent record of ownership or rights over property, whether held by the state or by individuals, that Roman large-scale mapping most clearly anticipated the modern world. If they had, one would suppose it to be a map connected with the periploi [sea itineraries]. Our sources point to only a few late glimpses of these transfers, as when Planudes took the lead in Ptolemaic research, for example. Here he explains his belief that the earth is a stationary sphere, at the center of the universe, which revolves about it daily. According to Ptolemy, even Marinus had made mistakes, either because he had consulted a€?too many conflicting volumes, all disagreeing,a€? or because he had never completed the final revision of his map.
However, Ptolemy rigorously applies the conical projection only to the northern part of his map of the world. The parallel bounding the southern limit of the habitable world is equidistant from the equator in a southerly direction as the parallel through Meroe is distant in a northerly direction. Yet this Ptolemaic theory was later mysteriously a€?re-interpreteda€? by Martin WaldseemA?ller in 1507 (see monograph #310 in Book IV) and again by Gerard Mercator in 1569 as a belief by Ptolemy in an all encircling great ocean.
Yet this Ptolemaic theory was later mysteriously a€?re-interpreteda€? by Martin WaldseemA?ller in 1507 (see monograph #310) and again by Gerard Mercator in 1569 as a belief by Ptolemy in an all encircling great ocean.
Viewed in its development through time, the map is a sensitive indicator of the changing thought of man, and few of these works seem to reflect such an excellent mirror of culture and civilization. Of a different order, but also of interest, are those maps made in comparatively recent times that are designed to illustrate the geographical ideas of a particular person or group in the past but are suggested by no known maps.
Many solutions to this problem were put forward, but it was solved once and for all by the Madaba map, which showed, between Jerusalem and Hebron, a place called Beth Zachari: the house of Zacharias.
The paucity of evidence of clearly defined representations of constellations in rock art, which should be easily recognized, seems strange in view of the association of celestial features with religious or cosmological beliefs, though it is understandable if stars were used only for practical matters such as navigation or as the agricultural calendar. The celestial globe had reinforced the belief in a spherical and finite universe such as Aristotle had described; the drawing of a circular horizon, however, from a point of observation, might have perpetuated the idea that the inhabited world was circular, as might also the drawing of a sphere on a flat surface. Aristotle also believed that only the ocean prevented a passage around the world westward from the Straits of Gibraltar to India. The result was that his observations served not merely to extend geographical knowledge about the places he had visited, but also to lay the foundation for the scientific use of parallels of latitude in the compilation of maps.
Many influential Romans both in the Republic and in the early Empire, from emperors downward, were enthusiastic Philhellenes and were patrons of Greek philosophers and scholars. In this respect, Rome had provided a model for the use of maps that was not to be fully exploited in many parts of the world until the 18th and 19th centuries.
But in order to reach an understanding of the historical processes involved in the period, we must examine the broader channels for Christian, humanistic, and scientific ideas rather than a single map, or even the whole corpus of Byzantine cartography. Bringing their box into the dining room each morning, the children each kept their box in their bedroom closet. While his proofs of the sphericity of the earth are still accepted today as valid, Ptolemy rejected the theory of the rotation of the earth about its axis as being absurd. To represent the known parts of the southern hemisphere on the same sheet, he describes an arc of a circle parallel to the equator, and at the same distance to the south of it, as Meroe [MA¦roe] is to the north, and then divides this arc in parts of the same number and size, as on the Parallel of Meroe.
That paradox notwithstanding, though, Ptolemya€™s depiction of a southern Afro-Asian continent and a land-locked Indian Ocean provided little comfort during the intervening 1,300 years to those early explorers, and later the Portuguese, in their attempts to find an all water route to India. The maps of early man, which pre-date other forms of written communication, were attempts to depict earth distributions graphically in order to better visualize them; like those of primitive peoples, the earliest maps served specific functional or practical needs. Excavations on this site revealed the foundations of a little church, with a fragment of a mosaic that contained the name a€?Zachariasa€?. What is certainly different is the place and prominence of maps in prehistoric times as compared with historical times, an aspect associated with much wider issues of the social organization, values, and philosophies of two very different types of cultures, the oral and the literate.
Later we encounter itineraries, referring either to military or to trading expeditions and provide an indication of the extent of Babylonian geographical knowledge at an early date. Another of a land, also in the north, where a man, who could dispense with sleep, might earn double wages, as there was hardly any night. There was, however, evidently no consensus between cartographic theorists, and there seems in particular to have been a gap between the acceptance of the most advanced scientific theories and their translation into map form. Viewed in this context, some of the essential cartographic impulses of the 15th century Renaissance in Italy are seen to have been already active in late Byzantine society. However, Marinusa€™ treatise on geography, with its maps, should still be ranked among the most important of the lost documents of the ancients, if for no other reason than that it was the foundation upon which Claudius Ptolemy built. The network is then obtained by joining the intersections to corresponding points on the equator.
The twenty-one parallels are spaced at equal lineal intervals and each one is designated by (1) the number of equinoctial hours and fractional hours of daylight on the longest day of the year and (2) the number of degrees and minutes of arc north of the equator. Maps were also frequently used purely for decoration; they furnished designs for Gobelins tapestries, were engraved on goblets of gold and silver, tables, and jewel-caskets, and used in frescoes, mosaics, etc. They do not go so far as to record distances, but they do mention the number of nights spent at each place, and sometimes include notes or drawings of localities passed through.
He probably had the first account from some sailor who had visited the northern latitudes in summer; and the second from one who had done the like in winter.
The influence of these views on Chinese cartography, however, remained slight, for it revolved around the basic plan of a quantitative rectangular grid, taking no account of the curvature of the eartha€™s surface. Montessori type equipment is stored on shelves in the childrena€™s rooms, dining room, or in a nearby closet. For example, the first parallel of latitude north of the equator was distant from it a€?the fourth part of an houra€? and a€?distant from it geometrically about 4A°15a€™a€?. It was not until the 18th century, however, that maps were gradually stripped of their artistic decoration and transformed into plain, specialist sources of information based upon measurement. As in Greek and Roman inscriptions, some documents record the boundaries of countries or cities.
At the same time Chinese geography was always thoroughly naturalistic, as witness the passage about rivers and mountains from the LA? Shih Chhun Chhiu. One other parallel is added south of the equator, identified with the Rhaptum promontory and Cattigara and about 8A° 25a€™ distant from a€?The Linea€?. All of the parallels north of the equator are located theoretically with the exception of three: Meroe, Syene and Rhodes. The first one, Clima I per Meroe, (so called because it passes through Meroe, near modern Shendi, a city of Africa at 17A° N latitude) was established traditionally as 1,000 miles below Alexandria and 300 miles from the torrid zone; it was also known as the royal seat and principal metropolis of Ethiopia [Africa].



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