[WATCH sb.]
† 1. A sand-glass or hour-glass used to measure the time of keeping watch, esp. on board ship. Also in fig. context. Obs.
1637. Rutherford, Lett., cclxxvi. (1891), 534. Time and tide carry us upon another life, and there is daily less and less oil in our lamps, and less and less sand in our watch-glass.
1701. Tuttell & Moxon, Math. Instr., 22. Watch-glass, used at Sea, to shift or change their Watches.
1769. Falconer, Dict. Marine (1780), Watch-glasses, a name given to the glasses employed to measure the period of the watch or divide it into any number of equal parts … so that the several stations therein may be regularly kept and relieved.
2. A thin piece of glass, usually concavo-convex in form, fitted into the case of a watch over the dial-plate.
1773. Pennsylv. Gaz., 16 June, Suppl. 2/2 [Advt.]. Watch glasses.
1831. Brewster, Optics, i. 4. A concave speculum is one which is hollow like the inside of a watch-glass.
1894. F. J. Britten, Former Clock & Watchm., 64. Watch glasses seem to have been introduced about 1600.
attrib. 1859. J. R. Greene, Protozoa, vii. 66. In Ophryoglena flavicans a remarkable body termed the ‘watch glass-like organ’ has been recently observed by Lieberkühn.
b. as a receptacle for small objects or portions of material to be subjected to scientific observation.
1757. Phil. Trans., L. 286. Pieces of these should be cut off while they are in the sea water, and placed in watch-glasses full of the same.
1818. Accum, Chem. Tests, 97. A small evaporating basin, or watch glass.
1880. L. S. Beale, How to work with Microscope (ed. 5), 54. Watch Glasses of various sizes should be kept by every observer.
1888. Rutley, Rock-Forming Min., 24. A watch-glass standing in a pill-box lid.
Hence Watch-glassful.
1830. Sir J. Herschel, Disc. Study Nat. Philos., II. vi § 182 (1851), 172. We almost forget that these great masses are made up of watch-glassfuls.
