ed by specifying their latitude and longitude.

It was not to be expected, however, that Ptolemy could accurately fix the
longitude and latitude of places in the remoter parts of the then known
world; his latitudes and longitudes are accordingly frequently erroneous,
but especially the latter. This arose partly from his taking five hundred
stadia for a degree of a great circle, and partly from the vague method of
calculating distances, by the estimate of travellers and merchants, and the
number of days employed in their journies by land, and voyages by sea. As
he took seven hundred stadia for a degree of latitude, his errors in
latitude are not so important; and though the latitude he assigns to
particular places is incorrect, yet the length of the globe, according to
him, or the distance from the extreme points north and south, then known,
is not far from the truth. Thus the latitude of Thule, according to
Ptolemy, is 64 degrees north, and the parallel through the cinnamon country
16 deg. 24' south, that is, 80 deg. 24' on the whole, a difference from the truth
of not more than six or seven degrees. It is remarked by D'Anville, and Dr.
Vincent coincides in the justice of the remark, that the grandest mistake
in the geography of Ptolemy has led to the greatest discovery of modern
times. Strabo had affirmed, that nothing obstructed the passage from Spain
to India by a westerly course, but the immensity of the Atlantic ocean;
but, according to Ptolemy's errors in longitude, this ocean was lessened by
sixty degrees; and as all the Portuguese navigators were acquainted with
his work, as soon as it was resolved to attempt a passage to India, the
difficulty was, in their idea, lessened by sixty degrees; and when Columbus
sailed from Spain, he calculated on sixty degrees less than the real
distance from that country to India. Thus, to repeat the observation of
D'Anville, the greatest of his errors proved eventually the efficient cause
of the greatest discovery of the moderns.

Beside the peculiar merit of Ptolemy, which was perceived and acknowledged
as soon as his work appeared, he possesses another excellence, which, as
far as we know, was first pointed out and dwelt upon by Dr. Vincent.
According to him, Ptolemy, in his description of India, serves as the point
of connection between the Macedonian orthography and the Sanscrit,
dispersing light on both sides, and showing himself like a luminary in the
centre. He seems indeed