[CLOCK sb.1] An instrument actuated by water for the measurement of time. Applied, e.g., to the CLEPSYDRA of the ancients, and to inventions of Sir Isaac Newton and others.
1601. Holland, Pliny, VII. lx. I. 191. This manner of Horologe or water-clocke, hee dedicated in the end within house.
1634. J. B[ate], Myst. Nat. & Art, 39. A Water-Clock, or a Glasse shewing the houre of the day.
1723. E. Stone, trans. Bion’s Math. Instrum., VIII. vii. (1758), 253. Of the Construction of a Water-Clock. This Clock is composed of a Metalline well soldered Cylinder,… wherein is a certain Quantity of prepared water, and several little Cells, which communicate with each other by Holes near the Circumference.
1727. Stukeley, in Turnor, Grantham (1806), 177. Sir Isaac’s water clock … resembled pretty much our common clocks…. There was a dial plate at top with figures of the hours. The index was turned by a piece of wood, which either fell or rose by water dropping.
1825. Fosbroke, Encycl. Antiq., 347. Water-clock, A new kind was invented in Italy about the middle of the seventeenth century. A cylinder, divided into several small cells, was suspended … in a frame, in which the hours’ distances, found by trial, were marked out. As the water flowed from one cell to another, it changed very slowly the centre of gravity of the cylinder, and put it in motion.
1855. J. H. Newman, Callista, vi. (1856), 47. Here the rushing of the water-clock, which measured time in the neighbouring square, ceased, signifying thereby that the night was getting on.
1894. Boase, Register Exeter Coll. (O.H.S.), p. lxxxix. [16th c.] Logic lectures were given from 6 to 7 in the morning,… The time was reckoned by a waterclock.
