Popular Science Monthly/Volume 16/February 1880/Maps and Map-Making Before Mercator
By CHARLES P. DALY, LL. D.
[ABRIDGMENT OF AN ADDRESS BEFORE THE GEOGRAPHICAL SOCIETY.]
THE materials for the history of cartography, or the art of map-making, are scanty. I propose to give a brief account of what we knew about it before the time of Gerard Krehmer, better known by his Latinized name of Mercator, who produced a large map of the world more than three centuries ago.
It is generally thought that the art of pictorial representation is older than the art of writing, and, if this be so, it is probable that the art of representation by maps is very ancient. Such delineations are in use among very primitive peoples. The Esquimaux understood the charts of Parry and Ross, and the North American Indians make rude maps, which they find serviceable to them.
One of the earliest things known in the nature of a map is the ground-plan of a town, now in the Koyunjik Gallery of the British Museum, which has been identified by Mr. Loftus as representing with minute accuracy the ground-plan of Susa, the Shushan of the Bible, a city of remote antiquity, situated on one of the streams that flow into the lower Euphrates, a little to the north of the head of the Persian Gulf, the country whence the people or race came that built Babylon, and founded the Chaldean civilization. The age of this topographical work is unknown, but it is assumed to be as old, at least, as the seventh century before Christ. It represents, in a rude form of design, the plan of the town, its walls, the citadel, the king's palace, and a central square surrounded on three sides by what is either a wall or a colonnade of buildings of uniform character. On the remaining square is a large gateway, and the suburbs surrounding the town are represented as planted with date-trees and interspersed with buildings to the banks of the river.
The Egyptians had maps, although but little is known of them. There is a papyrus preserved in the museum at Boolak containing a map of Lake Mœris, on the Nile. It shows the plan of the basin with its canal, and the position of towns and of certain sanctuaries upon the borders of the basin, with explanatory texts giving information respecting these places. There is also an old Egyptian map preserved at
Fig. 1.—Homer's World.
Turin of what is now Wady Alaiki, where the Nubian gold-mines were situated, in the land anciently called Aki-ta. It is a mountainous country, of dreary, sterile, waterless valleys, where men and beasts died upon the roads to these mines. The map shows the mountain-tracts, the rocks, and the places where gold was found, the ore-bearing mountains being marked in red color. It also shows the wells, a temple erected to Ammon on the mountain, and the appurtenances and buildings in the gold-districts. The roads, which had been abandoned, leading to the sea, are also given. "Nothing," says Brugsch Bey, "is forgotten calculated to give the spectator an idea of the state of the region, even to the stones and the scattered trees along the roads." This description is sufficient to show that the Egyptians knew the value of maps, and that they made and used them. These gold-mines were worked in the reign of Rameses II., and if this map was made at that period, as from the description given of it would seem to be the fact, then it is the oldest map known.
It was very different, however, with their neighbors, the Phœnicians. They were the great maritime nation of antiquity, making constant voyages along the coasts of the Mediterranean on either side, and along the western coast of Europe, as far as Great Britain, and possibly farther. The outlines of a coast once seen would, it is true, be sufficiently preserved in the memory for the practical purposes of navigation; but a people who had extended their voyages so far, who had established so many colonies, and to whom is attributed the invention of the alphabet, would naturally be led to the construction of charts,
Fig. 2.—Map of Hecatæus, b. c. 500.
from their utility, as well as maps to give some general idea of the world, of which they knew more than any other people. A jealous commercial policy kept them from imparting their knowledge to others, so that we do not know whether they had maps or charts; which is not remarkable, as we know, in fact, so little respecting them.
It is from the Greeks that we get our earliest knowledge of geographical maps. The first information we have upon the subject is from passages in Herodotus and Strabo. Strabo says that Anaximander, who was born b. c. 612, was the first who represented the world upon a map. Diogenes Laertes ascribed to him the invention of geographical maps, and also of the gnomon. But this he probably introduced into Greece, as it was in earlier use among the Chaldeans. Herodotus says that Aristagoras, when he went (504 b. c.) to Cleomenes, the King of Sparta, to induce him to invade Persia, produced before the Spartan king "a bronze tablet, upon which the whole circuit of the earth was engraved, with all its seas and rivers."
Hecatæus, who lived in the same century with Anaximander, is believed to have corrected and improved the map drawn by Anaximander. Hecatæus was, for his time, an extensive traveler. He was well acquainted with Egypt and Western Asia, and embodied the information he had collected in his travels in two geographical works, that have not come down to us, which were of great authority for several centuries after his time.
What these early maps were we do not know, but can form a reasonable conjecture. The earth at that time was supposed to be a flat circular plain, or disk, the broadest part being from east to west, which was entirely surrounded by an ocean, or great river, that washed it upon all sides. In about the center of this plain Greece was supposed to be situated. The great central sea of the inhabited region was the Mediterranean. The farthest point known at the west was the Straits of Gibraltar, then called the Pillars of Hercules. The southern part comprised the north of Africa as far as the deserts; while the region north embraced the countries bordering upon the Mediterranean, and an unknown hyperborean land farther to the north, with the Euxine and Caspian Seas at the northeast. The farthest eastern point known was about the western limit of India. This was what would then be contained in a map as a representation of the earth. The sun was supposed to pass under and around this flat plain, which was then the mode of accounting for the changes of day and night. The space beneath was supposed to be a great vault, called Tartarus, the abode of the spirits of the wicked among men, as the region corresponding to it, above the plain, was the heaven, or abode of the gods. The unknown region beyond the Pillars of Hercules was filled up with creations of the fertile imagination of the Greeks. To the northwest and
Fig. 3.—Hipparchus, 100 b. c.
north were the Cimmerians, a people living in perpetual darkness; and the hyperboreans, a race supposed to be exempt from toil, disease, or wars, who enjoyed life for a thousand years in a state of undisturbed serenity. To the west of Sicily were the enchanted islands of Circe and Calypso, and the floating island of Eolus. A little to the north of the Pillars of Hercules was the entrance to the infernal regions; and far out in the Western Ocean, beyond the limits of the known earth, was the happy region called Elysium, a land of perpetual summer, where a gentle zephyr constantly blew, where tempests were unknown, and where the spirits of those whose lives had been approved by the gods dwelt in perpetual felicity. Here, also, were the gardens of the Hesperides, with their golden apples guarded by the singing nymphs, who dwelt on the river Oceanus, which was in the extreme west, and the position of which was constantly shifted as geographical knowledge increased.
When the idea became firmly fixed in the mind of the learned that the earth was a sphere, it naturally followed among an artistic people like the Greeks that some attempt would be made to give a physical
Fig. 4.—Ptolemy's Map, a. d. 150.
representation of it, and accordingly we are told that Crates (b. c. 326) constructed a globe of the inhabited part of the earth, from the Arctic to the Tropic, in the form of a half-circle. The zone about the tropics he represented as an uninhabitable portion, entirely covered by water (a belief which existed for a long time afterward), and the southern half beyond as that of an unknown but inhabited region. Dicearchus the Messinian (b. c. 296), a very accomplished man, and the writer of several geographical works, which are lost, constructed a map of the world in an oval form, which appears to have been highly estimated, and to have been the model upon which subsequent maps were made. It is inferable from passages in the classic writers that the maps in use represented the unknown parts of the world, in conformity to the ideas deeply implanted in the popular mind by the poems of Homer and from other sources. With Eratosthenes, who died about the beginning of the second century before Christ, the science of geography may be said to have begun. He was the first to apply a purely scientific method to ascertain the magnitude of the earth; for, when a knowledge of the exact circumference of the globe was once obtained, the different countries and places could be arranged in these ancient maps, in their relative position to each other, far more accurately. The distances between places in what was then known as the inhabited part of the earth were previously ascertained by the number of days it took to go from one place to another, derived from the information of travelers and mariners.
To rectify the errors which became more apparent and confusing as the inhabited part of the world became better known, Eratosthenes devised, what has ever since been employed as the most accurate means of determining the circumference of the earth, the measurement of an arc of the meridian. He found a confirmation of the globular form of the earth in the fact that at Syene, in Upper Egypt, upon the tropic, the sun at noon on the day of the summer solstice was vertical—that is, that it cast no shadow, a well at the bottom being enlightened by its rays; while at Alexandria, upon the same day and time, it was distant from the zenith one fiftieth of the circumference of the circle. Eratosthenes obtained by this means the length of what is called an arc of the meridian, or a portion of the curved surface of the earth; and from this he was able, by a familiar rule, to determine the circumference of the whole circle.
The happy idea occurred to Hipparchus of applying to the earth the same method he had used in fixing the position of the stars in the celestial sphere. Regarding the earth as a great circle, which, like any other circle, is divisible into three hundred and sixty degrees, he so divided it, by lines of circles drawn perpendicularly from the poles to the equator, and by parallel lines at equal distances from the equator to the poles, which was the beginning of the division of the globe by lines of longitude and latitude into degrees.
The Romans, in their representation of the earth, at first followed Eratosthenes and Hipparchus. The Emperor Augustus ordered the geographers and designers to prepare for the use of the people a map of the habitable world which should represent fully the extent of the Roman Empire; and, from some fragments that were preserved, it is known that this map was a cylindrical projection of a great circle. The Romans, however, had a map for practical use, which they styled a descriptive itinerary, or, as they sometimes called it, "painted roads." This map was in the form of a band, about a foot wide and about twenty feet long, upon which the habitable earth was continuously represented along parallel spaces. It represented pictorially the great routes or roads of the empire, the position of places with the distances between them, the ranges of mountains, and the direction of rivers. This kind of map was mainly used for military purposes, and was regarded as a map of the world, for the vast extent of the Roman Empire comprised nearly all that was then known of the habitable world.
Fig. 5.—Claudius Ptolemy. (From an Old Map.)
Great progress was effected in map-making by Marinus of Tyre, who lived during the second century of our era. He studied with great care the works of his predecessors, collected all the information that was procurable from travelers and mariners, and produced a geographical work far beyond anything that had preceded it, illustrated by maps which were covered with a network of parallel and meridian lines, cutting each other at right angles, under which the different places were indicated according to their direction and distance from each other. His object was to put an end to the uncertainty about the position of countries and cities, by assigning to every locality or place its approximate latitude and longitude. He divided the globe into sections, each having an astronomical extent of fifteen degrees, and the places falling within these limits he put together in what he supposed to be their relative position to each other. He drew a line due east from the Fortunate Islands, and arranged countries and places in what he regarded as their proper position north and south of this line, so as to bring them alike under the proper zone or climate, as well as under the astronomical section he had devised.
Marinus was probably the first who undertook to combine systematically the results of astronomical observations with those of travelers and mariners in determining geographical positions. There being no delicate instruments to-indicate direction, altitude, or time, the latitudes and longitudes ascertained were at first, of course, erroneous. Marinus corrected earlier errors, and accumulated much new material for the preparation of a geographical work which premature death prevented him from perfecting.
The geography of his immediate successor, Ptolemy, which has fortunately come down to us, was written at least within half a century afterward, and, as Ptolemy himself says, was based upon the work of Marinus.
Ptolemy's labor was what in this day we should call editing a new and revised edition of an existing work. Ptolemy was a much better mathematician and astronomer, but evidently very inferior as a geographer to his predecessor. He undertook to correct Marinus's chief error by reducing his projection of the earth, from east to west, from 225° to 180°. In making this geometrical correction, however, he fell into a multitude of errors which, had he been a better geographer, he would readily have detected.
A period of twelve hundred years elapses from the time of Ptolemy to the inauguration, by Prince Henry the Navigator, of Portugal, of the spirit of maritime enterprise which led to the circumnavigation of Africa, and the discovery of the Continent of America. This long interval is marked by the decline in Europe of everything in the form of geographical knowledge, until a state of ignorance was reached in which little interest was felt in any branch of human learning. For the purposes of our inquiry it may be divided into three periods. The first was one of long-continued and nearly incessant wars, during which the destruction of everything was so great that, when it closed, there was little remaining but fragments of the ancient civilization. This was followed by a period of repose, ignorance, and torpor, to which succeeded another period, ending about the beginning of the fifteenth century, during which a limited few were slowly recovering a portion of the geographical knowledge that had been lost, and dimly groping their way to a true conception of the earth's form and laws.
Fig. 6.—Map of the World, Tenth Century.
But, though geographical knowledge declined during this interval, and from the sixth to the middle of the eleventh century the condition in Europe, except in Spain and in Ireland, was one of almost universal ignorance, there was throughout the whole of the period some attention, at least, given to geography—to the study of maps and to map-making. It was, it is true, very little, and the greater part of it tended more to obscure than to enlighten; but at no time was the interest in the subject wholly extinct. For several centuries after the time of Ptolemy, or up to the separation of the eastern from the western half of the Roman Empire, there was an almost uninterrupted study of geography in the schools of Alexandria, in which the fathers of the Church, the philosophers, the soldiers, and the emperors appear to have taken a warm interest. The maps then in use were itineraries or road-maps, which were very numerous, as they were of service to the soldiers during the wars that were then and which continued long afterward to be waged. In addition to these route-maps, general maps were also constructed, to show at a glance the form and proportions of the habitable globe; and in the fifth century Theodosius II. caused a survey to be made of the provinces of the empire, which occupied fifteen years, from which a large map of the empire was compiled. There was also a geographical school at Ravenna, in Italy, which, after Honorius (a. d. 404) made Ravenna the capital of the Western Empire, became very active, but the cartographical labors of this school appear to have been limited to the production of descriptive itineraries or painted route-maps. The authority of Ptolemy, during this period, declined. The Alexandrine geographers, no doubt, were better acquainted than he was with Asia, and knew the gross errors he had made in the configuration of countries and the position of places. But there was another and more potent cause that led to the discrediting of Ptolemy, as well as of all the ancient geographers. This was the disposition of the clergy, who for some centuries afterward
Fig. 7.—Arab Map of the World, a. d. 1009.
were the only learned class, to test all geographical knowledge by the standard of the Bible; and, as the Bible afforded no authority for the opinion of the ancient geographers that the earth is a globe, their ideas and their works were generally rejected as contrary to Holy Writ. In the middle of the sixth century Cosmos, who had been a merchant, an extensive traveler, and who afterward became a monk, was the writer of several geographical works, one of which has survived, in which he maintained that the idea of the earth being a globe was contrary alike to the Scriptures and to common sense; sustaining his views by ingenious arguments, which, in that age, were very convincing. Cosmos was not an ignorant man; on the contrary, his account of the countries with which he was acquainted was accurate and valuable, and it was his topographical knowledge which made him so formidable an antagonist in disputing the rotundity of the earth. "There are," he says, "false Christians, contemners of the authority of Scripture, who dare to maintain that the earth is a sphere. I combat this error, derived from the Greeks, by citations from Holy Writ." He then ridicules the idea that the earth revolves in space without axis, or anything to support it, and characterizes the belief of antipodes, or people living on the other side of a round globe, as old men's tales. Having thus disposed of the anterior belief, he proceeds to give his own idea of the earth, which he says no true Christian can doubt. It was, that the earth was an oblong plain, inclosed at its four extremities by huge walls of immense thickness, on which the firmament or vault of the heavens rested; and that near the north pole there was a high mountain, around which the sun, the moon, and the stars turned, the intervention of which mountain, at certain periods, caused eclipses.
We have now approached a period when Europe sank into the deepest ignorance, communication between places was broken up through the long continuance of wars; roads were destroyed, there was little or no commerce, for traveling was difficult and dangerous, and people in close proximity knew comparatively nothing of each other. Fortunately, however, this was not the state of things throughout the world. During the period that marks the rise, the maturity, and decline of the empire of the Arabs, or from the ninth to the thirteenth century, geography was assiduously cultivated by them as a science, especially in Bagdad, the capital of the Caliphs, and for a part of that period in Spain. It is to the Arabians that we owe the preservation of the work of Ptolemy, which they translated into Arabic and annotated. They determined the obliquity of the ecliptic, measured two arcs of the meridian, ascertained more accurately the longitude of places in Asia and about the Mediterranean, and enlarged descriptive geography by an account of the countries in Asia over which they had extended their conquests. As early as the ninth century they trafficked in the ports of the Indian Ocean, and had intercourse also at that time with China, through which probably the mariner's compass was brought to the Mediterranean. I may also mention in this connection that the Chinese, according to the statements of their own writers, had maps from a very remote period. These are described as representing the mountains, seas, rivers, lakes, plains, and basins, and were compiled by order of the emperors.
The Arabian geographers prepared an elaborate work (a. d. 830) founded upon Ptolemy. It is lost, but, from the references to it by Arab writers, we know that it gave a description of the habitable earth, and indicated the prominent places in different countries by their latitude and longitude, correcting, in the countries in which the Arabs were well acquainted, the gross errors in longitude of Ptolemy. It is from these tables of latitudes and longitudes that we know the wide extent of the geographical knowledge of the Arabs. Their corrections from west to east extended from Cadiz to the Indus, and they restored to their true position the places in the countries watered by the Euphrates and the Tigris. It is inferable, from statements of Arab writers, that they had maps constructed upon a mathematical basis. As these maps have not come down to us, it is supposed that they were rare, and were not intended for practical use, but constructed to aid the inquiries of the learned; for the Arabians pursued the study of geography mainly in its connection with astronomy, and were not, as we would understand the term, topographers, or only to a very limited
Fig. 8.—Edrisi's Map, a. d. 1154.
extent. It is rather for the preservation of what was previously known that we are indebted to the Arabs; for, though they studied geography with great assiduity, they can not be said to have greatly advanced it as a science.
Leaving the Arabs and their labors for the present, we will now return to the growth of cartography in Europe. We have maps designed to represent the earth as known, or particular parts of it, from the ninth to the fifteenth century; and which, from the rude efforts in the ninth century, exhibit the widest diversity in plan and execution. Some consist of straight parallel lines drawn across a circle, with the names of countries or places arranged along the lines. In others, the position of the Mediterranean is indicated simply by the name of the sea, and the names of countries and places are grouped about it in what was supposed to be their true position. In none of these early maps is there any attempt to give in curved lines the form of continents, or to indicate the boundaries of countries.
About the middle of the twelfth century, Roger, King of Sicily, determined to have a map of the world constructed from the best information
Fig. 9.—Italian Itinerary, Thirteenth Century.
that could then be obtained. For this purpose he sent intelligent men to various parts of the known world, to take the latitude and longitude of places, to collect itineraries, and gather every kind of information that was desirable. Fifteen years were spent in this preparatory work, and what had thus been obtained was intrusted to Edrisi, an Arabian geographer and traveler, who had been invited to the King's court, and from these materials Edrisi compiled a general map, which was engraved upon a round table, or globe of silver. In a manuscript in the National Library of Paris there are sixty-nine maps, supposed to have been copied from this silver globe, and there is a general copy of the map attached to a manuscript in the Bodleian Library at Oxford. This work of Edrisi was superior to anything that had preceded it in the middle ages. It appears to have given a new impulse to geographical inquiries, as it was compiled chiefly from the new materials that had been obtained; for Edrisi, upon examining the works of his Arabic predecessors and the work of Ptolemy, found that they had involved the general subject of geography in such doubt, uncertainty, and confusion, that in constructing his map he rejected them altogether as sources of authority. Edrisi also composed a geographical work which has survived. Wherever in it he had to refer to the fabulous and impossible things asserted by his predecessors, he generally accompanied the statement with the formula, "God only knows how this is."
To understand more clearly the rapid progress which was made in cartography in Europe in contrast with the little that was done for its improvement by the Arabs, it will be necessary to draw attention to the difference between the nature of the empire which they established and that era of maritime enterprise and commercial activity which sprang up, and after the twelfth century developed so rapidly in the cities of the Mediterranean. The Arabs had a vast empire, the great bulk of which had no connection with the sea. A highly imaginative people, they were more attracted by speculative inquiries respecting the earth as a whole, and therefore studied it more in its connection with astronomy than by those careful, patient, and practical topographical labors which constitute such an important part of geography. What could be done by astronomical observation to show the relative position of places they did; but they knew nothing of the Atlantic.
The people of the maritime cities of the Mediterranean had a field of activity very limited when compared with the great empire of the Arabs. It was the Mediterranean. Their pursuits were maritime. They were the carriers by water of products between Asia and Europe, and therefore became, what the Arabs never were, a nautical people. To them navigation and everything that tended to its improvement were of the highest interest, and they consequently gave great attention to details. They observed closely the outlines of coasts, carefully delineated them, and, as they had an eye for form and proportion, their maps, in design and execution, greatly excelled those of the Arabs.
These cosmographers knew very well the position of places to the pole, or geographical latitude, but in making their maps they drew no parallels of latitude, and paid less attention to longitude: for the mariners for whose use these maps were intended knew nothing about figures representing degrees of latitude and longitude, and they are consequently not found upon these maps. The distances on the land or over the sea were laid down from certain fixed points in the direction of the compass, and hence these maps are covered with a network of lines running in all directions from central points, called wind-roses (rose de vent), which, to persons familiar only with maps of the present day, are unintelligible.
In the fifteenth century, great acquisitions were made to the knowledge of the world, especially in Asia and Africa, by the journeys of Marco Polo and Cadamosto; and the result of this accumulation of new information was the construction, in 1457, of a large map of the world, by Fra Mauro. It was painted on the wall of a convent in Venice, and was, for its time, an admirable production.
Fra Carmelite was a friar who had established a geographical school in Venice, and whose acquisitions as a geographer were, for the time, so extensive that he received from his contemporaries the title of "the incomparable." He knew that the earth is a sphere—being well acquainted with Ptolemy, but did not follow Ptolemy's scientific method of so projecting the world as to give the longitude and latitude of places. It should be stated, as explanatory of the defective construction of general maps of the world at this time, and before it, that the belief of the ancients in the globular form of the earth was far from being generally accepted. Even among cosmographers there was great uncertainty as to its real form. Columbus thought it had the shape of a pear, and in fact its spherical form was not fully admitted until Magellan's vessel, in 1521, sailed around it. In Italy, however, the belief of the ancients, both as to the form and as to the motions of the earth, was revived as early as the middle of the fifteenth century.
About forty years before the map of Fra Mauro was executed, Prince Henry of Portugal, surnamed the Navigator, began to send out those expeditions along the western coast of Africa which were the beginning of that brilliant age of maritime exploration that led to the circumnavigation of the Cape of Good Hope, the discovery of the Continent of America, and the voyage of Magellan's vessel around the world. During this period of active discovery, the limits of Africa were greatly extended to the south, a vast continent was revealed by the discovery of America, and, the knowledge of the earth being thus largely augmented, a general map of the world bad to be differently arranged and represented by new methods.
The first map upon which the discoveries of Columbus appear is that of John Ruysch, in the edition of Ptolemy printed in Rome in
Fig. 10.—Mercator's First Map, a. d. 1538.
1508. Ruysch adopted the method of Ptolemy of projecting the earth in the form of a cone, with the Arctic at the summit, but so expanding the cone as to bring in the Western Hemisphere and show the islands and a part of the mainland discovered by Columbus and others. In 1511 Bernard Sylvanus produced in his edition of Ptolemy a general map of the world, upon what has since been called the cordiform or heart-shaped projection, which, while giving the whole of the geographical features of the earth, was, from the curve and sweep of the parallels of both latitude and longitude, better adapted than anything that had preceded it to convey upon a plane surface a general idea of the earth's globular form. In this map the newly discovered continent of America, under the name of "The Land of the Holy Cross," was laid down more fully and accurately than in the preceding map of Ruysch. In the following year, 1512, a Polish geographer, John de Stobnicza, in an introduction to Ptolemy, published a map which I regard as of great interest, as it was, as far as I have been able to ascertain, the first attempt to project the spherical surface of the earth upon a plane. If I am right in this supposition, it was the parent of the mode now in use in all atlases of representing in a map of the world both sides of the globe upon a flat surface by two planispheres, or circular maps joined together, one of which includes Europe, Asia, and Africa, and the other America, North and South. This map was constructed to represent that half of the globe which was unknown to Ptolemy, or substantially what is now known in maps of the world as the Western Hemisphere.
The main object of this interesting map was to show where this newly discovered land was situated, and place it in its true position with respect to the whole globe. The map is but a partial or subspherical projection, being cut off at the seventieth degree north latitude, and at the fortieth degree south latitude. The Continent of America, North and South, is represented as running northwesterly to the center of the map, and as extending from 70° north latitude to 40° south latitude, the shape of the continent as then understood being evidently derived from a chart, not then published, which, from an inscription upon it, is supposed either to have been drawn by Columbus, or under his direction. The breadth and general shape of South America, though rudely given, are remarkably correct. The isthmus separating South from North America is laid down, but exaggerated in length; and a small portion of North America is given, its extension to the west being left undefined. The position which the whole continent occupies as a part of the globe is, as would be expected, not correctly laid down, but, as a conjectural representation of its exact position, the map was for that time (a. d. 1512) a very remarkable production.
I have dwelt upon this map, because it has not received from geographers the attention it deserves; and for the further reason that it furnishes a striking illustration of the slow progress of geographical knowledge; for the projection of maps of the world, upon the same scientific method, did not come into general use until about the beginning of the last century, or nearly two hundred years afterward.
In 1520 Peter Benewitz constructed a map of the world in the form of a heart, after the method of Sylvanus, which has acquired a celebrity as the first map upon which the name of America appears.
In 1531 Oronce Fine undertook to improve this by a projection in the form of a double heart, so as to give, by that method, upon a plane or flat surface, both sides of the globe; and in 1538 Mercator, then a young man of twenty-eight, published a map of this double-heart projection, making many corrections, especially in respect to the Continent of America, of which only one copy is known to exist, attached to an
edition of Ptolemy of 1578, that belonged to Mercator, and which has been liberally deposited by a member of our council, J. Carson Brevoort, in the library of our society.
All these maps, in their delineation of the outline of countries, were very defective, and especially in respect to the Continent of America. The accessions to geographical knowledge had become so vast and the details were so enormous that the work of giving the whole of the surface of the earth, as far as known, with all the details of continents, oceans, gulfs, bays, straits, rivers, mountain-ranges, and islands, with any marked approximation to correctness, was not accomplished until Mercator produced his great map of the world in 1569; which, when the fullness of its details is considered in connection with the new and scientific method upon which he projected it, entitles him to the appellation of the father of modern cartography. In this map he introduced what has ever since been known as Mercator's projection, which not only gave the world in one view, but by an ingenious and simple contrivance showed the most effectual way for a vessel to sail in a straight line over a curved surface, and thereby solved what was before one of the most difficult problems in navigation. That projection constitutes, down to the present day, the basis of every chart that is constructed to guide the mariner in his way over the ocean, and the map of the world on his projection is to be found in nearly every English or American atlas that has been published for a century and more, and yet the inquirer would search in vain in any work in the English language for the particulars of Mercator's life, or for any satisfactory account of what he did. How little is known respecting him, even by nautical men, will be sufficiently indicated when I state that, upon speaking about him not very long ago to a distinguished admiral, he looked at me and exclaimed: "What! was there such a man as Mercator? I always supposed Mercator's projection meant the merchant's projection."