In most of the maps of the first description, Europe, Asia, and Africa are laid down as forming one immense island, and Africa is not carried so far as the equator.  One of the most celebrated of these maps was drawn up by Marin Sanuto, and inserted in his memorial presented to the pope and the principal sovereigns of Europe, for the purpose of persuading and shewing them, that if they would oblige their merchants to trade only through the dominions of the Caliphs of Bagdat, they would be better supplied and at a cheaper rate, and would have no longer to fear the Soldans of Egypt.  This memorial with its maps was inserted in the Gesta Dei per Francos, as we are assured by the editor, from one of the original copies presented by Sanuto to some one of the princes.  Hence, as Dr. Vincent remarks, it probably contains the oldest map of the world at this day extant, except the Peutingerian tables.  Sanuto, as we have already noticed, in giving an abstract of the commercial information contained in his memorial, lived in 1324.

In the monastery of St. Michael di Murano, there is a planisphere, said to be drawn up in 1459, by Fra Mauro, which contains a report of a ship from India having passed the extreme point south, 2000 miles towards the west and southwest in 1420.

Ramusio describes a map, supposed to be this, which he states to have been drawn up for the elucidation of Marco Polo’s travels.

On this map, so far as it relates to the circumnavigation of Africa, Dr. Vincent has given a dissertation, having procured a fac-simile copy from Venice, which is deposited in the British Museum; the substance of this dissertation we shall here compress.  He divides his dissertation into three parts.  First, whether this was the map noticed by Ramusio, and by him supposed to be drawn up to elucidate the travels of Marco Polo.  On this point he concludes that it was the map referred to by Ramusio, but that his information respecting it is not correct.  The second point to be determined is, whether the map procured from Venice was really executed by Mauro, and whether it existed previous to the Portuguese discoveries on the west coast of Africa.  Manro lived in the reign of Alphonso the Fifth, that is between 1438 and 1480; the whole of this map, therefore, is prior to Diaz and Gama, two celebrated Portuguese navigators.  Consequently, if it can be proved that the map obtained by Dr. Vincent is genuine, it must have existed previous to the Portuguese discoveries.  The proof of the genuineness of the map is derived from the date on the planisphere, 1459; the internal evidence on the work itself; and the fact that Alphonso, or Prince Henry of Portugal, who died in 1463, received a copy of this map from Venice, and deposited it in the monastery of Alcobaca, where it is still kept.  The sum paid for this copy, and the account of expenditure, are detailed in a MS. account in the monastery of St. Michael.