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CLIVE. 4; don, 1836) ; Malleson, Founders of the Indian Empire: Lord Clive (London, 1882) ; Malleson, Decisive Baltics of India (London, 1883) : Jlill, History of lirilish India, vol. iii. (London, 1858) ; Ornie. llistorij of the Mililarii Transuc- lions of the British yation. in Indostan (London. 1803) ; IMaoanlay, Essay on Clive (London, 1840). CLOACA, Ido-alcii (Lat., sewer) . The cloacce or drains were subterranean passages, usually built of stone, devised to carry off the spring or vaste water and the refuse of a Roman city. In Eome the early city was naturally drained by streams running through three valleys between the hills. Three main channels were built to con- fine these streams, receive the drainage, and eari-y it to the Tiber. The largest of these, crossing the Argiletuin, Forum, and Velabrum, was called, from its size, the Cloaca Iklaxima, though that of the Vallis Murcia and that near the Circus Flaminius rival it in size and solidity. A net- work of smaller passages empty into these main channels. The system as largely due to the Tar- quins. The Cloaca IMa.xima was built with three large arches, one within the other. The space in- closed by the innermost vault was upward of 13 feet in width, and of corresponding height. The arches were built of large blocks of stone, _ fixed together without cement, of the uniform size of rather more than five feet five inches long and three feet high. The flooring is paved like a Eoman road, and the side walls are built of Gabii stone, in blocks measuring sometimes 45 cubic feet. The sewer was kept in a .state of etticiency by a continuous stream of superfluous w^ater from the aqueducts. Large portions of the cloacic remain in some places still visible, but generally buried by the accumulation of soil, at a considerable depth below the present level of the streets. The mouth of the Cloaca Maxima at the Tiber is .still visible. During the Republic the surveillance of the Roman cloaca? was one of the duties performed by the censors. The Cloaca Maxima was repaired by Cato and bis colleagues in the censorship. Agrippa, when edile, obtained praise for his exertions in cleans- ing and repairing the eloacse, and is recorded to have passed through them in a boat. Under the Kmpire, officers called euratores cloacarum vrbis were appointed for their supervision. So thor- oughly was the city undermined by these large sewers that Pliny calls it urls pensilis, a city suspended in the air rather than resting upon the earth. Drains of the same description, but of smaller dimensions, existed in other ancient Ro- man cities. CLOCHES DE CORNEVILLE, Les, la UlAsli' dc kor'n'-vel'. A very popular operetta, in three acts, produced at the Folies Dramatiques in 1877. The amusing libretto is by Clairville and Charles Gabet, the music, from which many airs have become popular, by Robert Planquette. CLOCK (AS. clucge, Icel. kluhka, Ger. Gloche, bell, from ISfL. clocca, bell, from Olr. clocc. It. Gael, clofi, bell, clock, Welsh, Corn, cloch. Manx cla<jg, bell ) . A mechanical instrument for meas- uring and indicating the time of day. usually by a mechanism consisting of two distinct portions: First, a train or succession of toothed wheels for transmission to a definite point of a motive force, produced by a weight or spring; and. second, an escapement to regulate the expenditure of this i CLOCK. motive force with uniformity and requisite slow- ness. A watch is simply a portable clock, to be wori on the person, in which the motive force is a spring. A marine chronometer is a watch of unusual size, constructed and mounted with espe- cial care, for determining longitude at sea. See Watch : Ciiroxometer. IIi.STORic.L Developjiext. Among the prede- cessors of the clock, as time-measurers, are the sun-dial, the clepsydra or water-clock, and the hour-glass. (See Dial: Clepsydba ; HouR- Glass.) The clepsydra was a graduated trans- parent vase, in which water trickled through a hole in the bottom at such a rate that the reced- ing water marlced the passage of time. In the hour-glass sand was substituted for water. Among Eastern nations a great many curious mechanical devices were introduced into the con- struction of the clepsydra : the water was made to flow in tears from the eyes of automata ; a floating statiie. falling with the liquid, pointed to the passing hours, as indicated on the side of the glass: finally, a mechanism was introduced by which the water, as it fell, drop by drop, turned a little wheel, which moved the hands on the face of a dial, and so marked the hour. The next step was the construction of a time-indi- cator, wliose hands were moved by the action of falling weights instead of that of falling water. When this step was taken, and the first true clock constructed, is uncertain. Its invention is claimed by many peoples, from the Chinese. B.C. 2000, to the Germans of the eleventh century. Certain it is that clocks were in general use in churches and monasteries throughout the latter part of the Middle Ages, and that these ancient tower-clocks were the progenitors of all our mod- ern timekeepers. The oldest clock of which we have a complete description was set up in the tower of the palace of Charles V. of France, in 1379, by a German named Henry De Vick. This primitive clock was constructed on the mechanical principle which is the basis of all modern timekeepers. This principle, as formulated by E. A. Marsh, is "that the power stored up in a raised weight or coiled spring shall be communicated to a train of wheels which are set revolv- ing, and that the force or motion shall be cut up into a succession of minute but equal impulses by convert- ing a rotary into a vibratory motion. The last and quickest wheel of the train shall have its teeth so formed that they are caught and escape alternately, and hence the wheel is called the 'scape - wheel.' and, from its resemblance to a crown, the 'crov-n- wheel.' The bar and staff, which, with its projections, catch and release the teeth, is termed the 'escapement,', and it is through this device that the rotary is converted Fig. 1. MECHANISM OP TICK'S CLOCK.