48.

Syene is a city situated on the borders of Ethiopia and Egypt. Elephantina is an island in the Nile, at the distance of half a stadium in front of Syene; in this island is a city with a temple of Cnuphis, and a nilometer like that at Memphis. The nilometer is a well upon the banks of the Nile, constructed of close-fitting stones, on which are marked the greatest, least, and mean risings of the Nile; for the water in the well and in the river rises and subsides simultaneously. Upon the wall of the well are lines, which indicate the complete rise of the river, and other degrees of its rising. Those [Pg 264]
[CAS. 817]who examine these marks communicate the result to the public for their information. For it is known long before, by these marks, and by the time886 elapsed from the commencement, what the future rise of the river will be, and notice is given of it. This information is of service to the husbandmen with reference to the distribution of the water; for the purpose also of attending to the embankments, canals, and other things of this kind. It is of use also to the governors, who fix the revenue; for the greater the rise of the river, the greater it is expected will be the revenue.

At Syene there is a well which indicates the summer solstice, because these places lie under the tropical circle,887 [and occasions the gnomons to cast no shadows at mid-day].888 For on proceeding from the places in our country, in Greece I mean, towards the south, the sun is there first over our head, and occasions the gnomons to be without shadows at noon. When the sun is vertical to us, it must necessarily cast its rays down wells, however deep they may be, to the water. For we ourselves stand in a perpendicular position, and wells are dug perpendicular to the surface.

Here are stationed three Roman cohorts as a guard.