[Illustration: North-western portion of Juan de la Cosa's map of 1500. Only a few of the names are given; the network of compass-lines is omitted]
For the understanding of La Cosa's map it must be remarked first of all that it is a compass-chart, and that it takes no notice of the magnetic variation on the American coast. This explains the fact that, for instance, lines of coast which in reality run from west to south-west, are made to appear on the chart as running from west to east. Furthermore, the latitude of the coast of North America is made too northerly, through coasts which, for instance, lie magnetic west of Ireland, being placed on the chart true west of it. In this way Cape Breton (or Cape Race in Newfoundland ?) can be brought to about the same latitude as the south of Ireland, whereas in reality it lies nearly 5° farther south.
The coast marked with five English flags is, of course, the land discovered by Cabot. That La Cosa had a map of this district is further shown by the details, which distinguish it from his delineation of the remainder of the North American coast, but which give it a resemblance to that part of South America which is marked with Spanish flags and of which he had a map. Curiously enough only part of the English district has names; we must suppose that this is the coast that Cabot is said to have sailed along. La Cosa's representation of the rest of the North American coast is doubtless guesswork, although it has features which bear a remarkable resemblance to reality; but it is not altogether impossible that he may have had oral or written reports of later voyages (?), which are unknown to us.
La Cosa's map is in complete agreement with the statements in the letters of Pasqualigo, Soncino, and the two Spanish Ambassadors. Soncino says that the country lies four hundred Italian leagues to the west of England, while both Puebla and Ayala say that they believe the distance to be no more than four hundred Spanish leagues. On the other hand, according to Pasqualigo, Cabot said that at a distance of seven hundred Italian leagues he had discovered the mainland of the kingdom of the Great Khan, and that he had sailed [i.e., after having sailed ?] three hundred leagues along the coast. It has been thought that there is here a disagreement between the four hundred leagues of the three first-named and the seven hundred of Pasqualigo, but if we interpret it, in what must be the most reasonable way, as meaning that the distance of seven hundred leagues does not refer to the nearest land, but to the most distant, where Cabot thought that he had at last come within the boundaries of the kingdom of the Great Khan (China) and did not venture to go farther, then we have complete agreement, since the three hundred leagues he must first have sailed along the coast must be deducted in order to get the distance from England to the nearest land. The length of a Venetian "lega," or a Spanish "legua," cannot be precisely determined. If we assume [cf. Kretschmer, 1909, pp. 63, ff.] that between 20 and 17-1/2 went to a degree of latitude, each league would correspond to between 3 and 3.43 geographical miles (minutes), or between 5.6 and 6.3 kilometres. According to the former estimate (three miles), four hundred leagues will be about equal to 1200 miles, and seven hundred leagues to about 2100 miles.[302] The first distance is, at any rate, a good deal too small, while the second is too great. This may easily be explained by Cabot, or his crew, having naturally wished to make the voyage to the newly discovered country appear as little deterrent as possible, and, therefore, having underestimated the distance, while, desiring to make the country itself as large as possible, they greatly over-estimated the length of their sail along the coast. That the voyagers really supposed the distance to the newly discovered land to be four hundred leagues from Ireland agrees also with Soncino's statement that the Bristol sailors thought the voyage would not occupy more than fifteen days from Ireland.