[f. CYANO- 1 + -METER, after F. cyanomètre (1791 in Hatzfeld).] An instrument for measuring the intensity of the blue of the sky.

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1829.  Nat. Philos., Optics, xviii. 65 (Useful Knowl. Soc.). In order to measure this intensity, M. Saussure contrived an instrument called a Cyanometer.

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1852.  Th. Ross, trans. Humboldt’s Trav., I. ii. 84. We beheld with admiration the azure colour of the sky. Its intensity at the zenith appeared to correspond to 41° of the cyanometer.

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  Hence Cyanometric a.; Cyanometry, measurement of the intensity of the blue of the sky.

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1853.  Pharmac. Jrnl., XII. 499. A New Cyanometric Process … founded upon the reaction of iodine upon the cyanides.

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1885.  Encycl. Brit., XVIII. 481. Peltier’s other papers … are devoted in great part to atmospheric electricity, water-spouts, cyanometry and polarization of sky-light.

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