Elementary treatise on physics experimental and applied for the use of colleges and schools (1890)
Ganot, A. (Adolphe), 1804-1887, Atkinson, E. (Edmund) · New York : W. Wood · leaf 623
is instrument, as its name indicates, is de-signed for the examination of the eye, and was invented in 1851 by ProfessorHelmholtz. It consists :—r. Of a concave spherical reflector of glass ormetal, M (figs. 590, 591), in the middle of which is a small hole about asixth of an inch in diameter. The… … Fig. 596. a lamp put beside him, E. The screen serves to shade the light from hishead, and keep it in darkness. The observer, A, holding in one hand thereflector, employs it to concentrate the light of the lamp near the eye, B,of the patient, and with his other hand holds the achromatic lens,…
Physics
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