Cunningham's Ancient Geography of India c7.31

c7.31

If the measures of distance by sea had been increased in the same proportion, or had been estimated at the same value, as the measures of distance by land, all the places would have retained the same relative positions. But the consequence of Ptolemy's unequal estimate of the value of land and sea distances was to throw all the places determined by land measurement too far to the east; and as this error went on increasing the further he advanced, his eastern geography is completely vitiated by it. Thus Taxila, which is almost due north of Barygaza, is placed 11° to the east of it; and the mouth of the Ganges, which was fixed by land-measurement from Taxila and Palibothra, is placed 38° to the east of the mouth of the Indus, the true difference being only 20°. In fig. 4 of the accompanying plate of small maps I have given an outline of Ptolemy's 'Geography of India.' By referring to this it will be seen at a glance that, if the distance between the mouths of the Indus and Ganges were reduced from 38° to 20°, the point of Cape Comorin would be thrown far to the south, and would form an acute angle very nearly in its true position. The amount of error in Ptolemy's value of land distances is well shown in the difference of longitude between Taxila and Palibothra. The former he places in 125° and the latter in 143°, the difference being 18°, which is nearly one-third too much, as the actual difference