from which the water is drawn in the same manner to water the gardens and fruit trees; so that it is no exaggeration to say, that there are in Egypt above 200,000 oxen daily employed in this labor." Shaw's name of Persian wheel has been since given more particularly to a wheel with buckets, either fixed or suspended on pins, at its periphery. Mortimer's husbandry, I. 18, Duhamel III. II., Ferguson's Mechanic's plate, XIII; but his figure, and the verbal description of the Universal History, prove that the string of buckets is meant under that name. His figure differs from Evans' construction in the circumstances of the buckets being round, and strung through their bottom on a chain. But it is the principle, to wit, a string of buckets, which constitutes the invention, not the form of the buckets, round, square, or hexagon; nor the manner of attaching them, nor the material of the connecting band, whether chain, rope, or leather. Vitruvius, L. x. c. 9, describes this machinery as a windlass, on which is a chain descending to the water, with vessels of copper attached to it; the windlass being turned, the chain moving on it will raise the vessel, which in passing over the windlass will empty the water they have brought up into a reservoir. And Perrault, in his edition of Vitruvius, Paris, 1684, fol. plates 61, 62, gives us three forms of these water elevators, in one of which the buckets are square, as Mr. Evans' are. Bossut, Histoire des Mathematiques, i. 86, says, "the drum wheel, the wheel with buckets and the _Chapelets_, are hydraulic machines which come to us from the ancients. But we are ignorant of the time when they began to be put into use." The _Chapelets_ are the revolving bands of the buckets which Shaw calls the Persian wheel, the moderns a chain-pump, and Mr. Evans elevators. The next of my books in which I find these elevators is Wolf's Cours de Mathematiques, i. 370, and plate 1, Paris 1747, 8vo; here are two forms. In one of them the buckets are square, attached to two chains, passing over a cylinder or wallower at top, and under another at bottom, by which they are made to revolve. It is a nearly exact representation of Evans' Elevators. But a more exact one is to be seen in Desagulier's Experimental Philosophy, ii. plate 34; in the Encyclopedie de Diderot et D'Alembert, 8vo edition of Lausanne, 1st volume of plates in the four subscribed Hydraulique. Norie, is one where round eastern pots are tied by their collars between two endless ropes suspended on a revolving lantern or wallower. This is said to have been used for raising ore out of a mine. In a book which I do not possess, L'Architecture Hydraulique de Belidor, the 2d volume of which is said [De la Lande's continuation of Montucla's Historie de Mathematiques, iii. 711] to contain a detail of all the pumps, ancient and modern, hydraulic machines, fountains, wells, &c., I have no doubt this Persian wheel, chain pump, chapelets, elevators, by whichever name