Syene
Syene [1]
is represented by the present Aswam or Essudn, which exhibits few remains of the ancient city, except some granite columns of a comparatively late date and the shrine of a small temple. This building has been supposed by late travelers to have contained the famous well of Strabo (Geog. 17 p. 817), into which the rays of a vertical sun were reported to fall at the summer solstice a circumstance, says the geographer, that proves the place "to lie under the tropic, the gnomon at midday casting no shadow." But although excavations have been carried on considerably below the pavement, which has been turned up in search of the well it was thought to cover, no other results have been obtained than that this shrine was a very improbable site for such an observatory, even if it ever existed; and that Strabo was strangely misinformed, since the Egyptians themselves could never in his time have imagined this city to lie under the tropic; for they were by no means ignorant of astronomy, and Syene was, even in the age of Hipparchus (B.C. 140, when the obliquity of the ecliptic was about 23 51' 20"), very far north of that line. The belief that Syene was in the tropic was, however, very general in the time of the Romans, and is noticed by Seneca, Lucan, Pliny, and others. But, as, Sir J. G. Wilkinson remarks, "a well would have been a bad kind of observatory if the sun had been really vertical; and if Strabo saw the meridian sun in a well, he might be sure he was not in the tropic"(Mod. Egypt and Thebes, 2, 286). The same writer adds," Unfortunately, the observations of the ancient Greek writers on the obliquity of the ecliptic are not so satisfactory as might be wished; nor are we enabled, especially as La Grange's theory of the annual change of obliquity being variable is allowed to be correct, to ascertain the time when Aswan might have been within the tropic, a calculation or traditional fact in which, perhaps, originated-the erroneous assertion of Strabo." The latitude of Aswan is fixed by Wilkinson at 240 5' 30", and the longitude is usually given as 32 55'.
