History of Cartography

In China, maps in the olden time were engraved on bronze or stone, but after the loth century they were printed from wood blocks. Among the more important productions of more recent times may be mentioned a map of the empire, said to be based upon actual surveys by Yhang (721), who also manufactured a celestial globe (an older globe by Ho-shing-tien, 4m in circum ference was produced in 450), and an atlas of the empire on a large scale by Thu-sie-pun (1311-1312) of which new enlarged editions with many maps were published in the i6th century and in 1799. None of these maps was graduated, which is all the more surprising as the Chinese astronomers are credited with having made use of the gnomon as early as i000 B.C. for determining latitudes.

In the case of Japan, the earliest reference to a map is of 646, in which year the emperor ordered surveys of certain provinces to be made.

Portolano Maps.

During the long period of stagnation in cartography, which we have already dealt with, there survived among the seamen of the Mediterranean charts of remarkable accuracy, illustrating the Portolani or sailing directories in use among them. They antedate 127o, and in the eastern part of the Mediterranean embody materials available even in the days before Ptolemy, while the correct delineation of the west seems to be of a later date, and many have been due to Catalan seamen. These charts are based upon estimated bearings and distances between the principal ports or capes, the intervening coast-line being filled in from more detailed surveys. The bearings were dependent upon the seaman's observation of the heavens, for these charts were in use long before the compass had been introduced on board ship (as early as 1205, according to Guiot de Provins). It is therefore misleading to describe them as Compass or Loxodromic charts, and they are now known as Portolano charts.

None of these charts is graduated, and the horizontal and vertical lines which cross many of them represent neither parallels nor meridians. Their most characteristic feature, and one by which they can most readily be recognized, is presented by groups or systems of rhumb-lines, each group of these lines radiating from a common centre, the central group being generally encircled eight or 16 satellite groups. Each chart was furnished with scale of Portolano miles whose length was only 1,233 metr On these old charts the Mediterranean is delineated with surpr ing fidelity. The meridian distance between the Straits of Gibr, tar and Beirut in Syria amounts upon them to about 3,00o Port lano miles, equal in lat. 36° N. to as compared with actual difference of 41.2°, and a difference of 61° assumed by Ptolemy. There exists, however, a serious error of orientation, due, according to Prof. H. Wagner, to the inexperience of the car tographers who first combined the charts of the separate basins of the Mediterranean so as to produce a chart of the whole. This

accounts for Gibraltar and Alexandria being shown as lying due east and west of each other, although there is a difference of 5° of latitude between them, a fact known long before Ptolemy. The oldest of these maps which have been preserved, the so-called "Pisan chart," which belongs probably to the middle of the 13th century, and a set of eight charts, known by the name of its former owner, the Cavaliere Tamar Luxoro, of somewhat later date, are both the work of Genoese artists. Petrus Vesconte, who worked in 1311 and 1327, is the draughtsman of the maps illustrating Marino Sanuto's Liber secretorum fidelium crucis, which was to have roused Christendom to engage in another crusade (fig. 8).

The expansions of Portolano maps into maps of the world re semble the wheel maps of an earlier period. This is the character of the map of Petrus Vesconte of 132o, of that of Giovanni Leardo (1448) and of a Catalan map of 1450.

Very different in character is the Catalan map of 1375, for its author, discarding Ptolemy, shows India as a peninsula. On the other hand, an anonymous Genoese would-be reformer of maps (1457), still adheres to the erroneous Ptolemaic delineation of southern Asia, and the very same error is perpetuated by Hen ricus Marvellus Germanus on a rough map showing the Portuguese discoveries up to 1489. None of these maps is graduated, but if we give the Mediterranean a length of 3,00o Portolano miles, equivalent in 36° N. to 41°, then the longitudinal extent of the old world as measured on the Genoese map of 1457 would be 136° instead of i77° or more as given by Ptolemy.

The Revival of Ptolemy.

Ptolemy's great work became known in western Europe after Jacobus Angelus de Scarparia had translated it into Latin in 141o. This version was first printed in 1475 at Vicenza, but its contents had become known through ms. copies before this, and their study influenced the construction of maps in two respects. They led firstly to the addition of degree lines to maps, and secondly to the compilation of new maps of those countries which had been inadequately represented by Ptolemy. Thus Claudius Clavus Swartha (Niger), who was at Rome in 1424, compiled a map of the world, extending westward as far as Greenland. The learned Cardinal Nicolaus Krebs, of Cusa (Cues) on the Moselle, who died 1464, drew a map of Ger many which was first published in 1491 ; D. Nicolaus Germanus, a monk of Reichenbach, in 1466 prepared a set of Ptolemy's maps on a new projection with converging meridians; and Paolo del Pozzo Toscanelli in 1474 compiled a new chart on a rectangular projection, which was to guide the explorer across the western ocean to Cathay and India.