NILOMETER, an instrument used amongst the ancients to measure the height of the water of the river Nile during the periodical inundation. The word comes from Νιλος, Nile, and μετρον, measure. The Greeks more commonly called it Νιλομετρον. The nilometer is said, by several Arabian writers, to have been first set up, for this purpose, by Joseph during his regency in Egypt; and the measure of it was sixteen cubits, this being the height of the increase of the Nile which was then necessary to the fruitfulness of Egypt.
From the measure of this column, Dr Cumberland deduces an argument, in order to prove that the Jewish and Egyptian cubits were of the same length. In the Royal Library of Paris there is an Arabic treatise on nilometers, entitled Neil fi alnal al Nil, in which are described all the overflowings of the Nile, from the first to the 875th year of the Hegira. Herodotus mentions a column which had been erected in a point of the island of Delta, to serve as a nilometer; and there is still one in a mosque at the same place.
The following is Bruce's account of the nilometer. "On the point of the island Rhode, between Geeza and
Cairo, near the middle of the river, is a round tower enclosing a neat well or cistern lined with marble. The bottom of this well is on the same level with the bottom of the Nile, which has free access to it through a large opening like an embrasure. In the middle of the well rises a thin column of eight faces of blue and white marble, of which the foot is on the same plane with the bottom of the river. This pillar is divided into twenty pecks, of twenty-two inches each. Of these pecks the two lowermost are left, without any division, to stand for the quantity of sludge which the water deposits there. Two pecks are then divided, on the right hand, into twenty-four digits each; then on the left, four pecks are divided into twenty-four digits; then on the right, four, and on the left another four; again, four on the right, which completes the number of eighteen pecks from the first division marked on the pillar. Thus the whole, marked and unmarked, amounts to something more than thirty-six feet English." (See Bruce's Travels (vol. iii.), and also the article Egypt.)