Page:Travels to Discover the Source of the Nile - In the Years 1768, 1769, 1770, 1771, 1772, and 1773 volume 1.djvu/268

160 observation surely therefore is not worth recording, unless to shew the insufficiency or imperfection of the method; it cannot deserve the encomiums that have been bestowed upon it, if justice has been done to Eratosthenes' geodesique measures, which I do not, by any manner of means, warrant to be the case, because the measure of his arch of the meridian seems to have been conducted with a much greater degree of success and precision than that of his base.

the 22d, 23d, and 24th of January, being at Syene, in a house immediately east of the small island in the Nile (where the temple of Cnuphis is still standing, very little injured, and which Strabo, who was himself there, says was in the ancient town, and near the well built for the observation of the solstice) with a three-foot brass quadrant, made by Langlois, and described by Monsieur de la Lande, by a mean of three observations of the sun in the meridian, I concluded the latitude of Syene to be 24° 0′ 45″ north.

, as the latitude of Alexandria, by a medium of many observations made by the French academicians, and more recently by Mr Niebuhr and myself, is beyond possibility of contradiction 31° 11′ 33″, the arch of the meridian contained between Syene and Alexandria, must be 7° 10′ 48″, or 1′ 12″ less than Eratosthenes made it. And this is a wonderful precision, if we consider the imperfection of his instrument, in the probable shortness of his radius, and difficulty