It must ever be matter for regret that none of the sailing charts prepared by Vasco da Gama's pilots should have reached us. In tracing the progress of his expedition with the aid of charts we are consequently dependent upon compilations which, although contemporary, embody also materials brought home by other navigators.

One great drawback of all the charts available for our purpose is their small scale. This compelled their compilers to make a selection from the names which they found inserted upon the larger charts at their disposal, and this selection may not always have been a judicious one. The compilation of a map from discordant materials presents difficulties even in the present day, and these difficulties were much greater at a time when the compiler had not at his command trustworthy observations for latitude which would have enabled him to check the positions of intermediate places, and bring into agreement the records brought home by successive explorers. As an instance, we may mention that in the five maps which we shall bring more fully under notice, the latitude assigned to the Cape of Good Hope varies between 29° and 34° S., its true position being 34° 22′ S. As to longitudes, they had to be determined by dead reckoning, and it need not therefore surprise us if, on the maps referred to, the Cape is placed from 3° 50′ to 10° 20′ too far to the eastward.