Also sphærometer. [ad. F. sphéromètre: see SPHERO- and -METER.] An instrument for measuring the sphericality or curvature of bodies or surfaces.
1827–8. Herschel, in Encycl. Metrop. (1845), IV. 567. The ‘Spherometer,’ a delicate species of calibre contrived by M. Biot. Ibid. (1830), Study Nat. Philos., 355. The elegant invention of the sphræometer,… substituting the sense of touch for that of sight in the measurement of minute objects.
1876. Catal. Sci. App. S. Kens., 29. Spherometer for measuring spherical curves, with true gun-metal plane.
Comb. 1903. Nature, 12 March, 442/2. The spherometer-calliper, which, we believe, was used with success in the testing of the instruments employed in the transit of Venus expeditions.
