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January 19, 1901


Author Affiliations

Oculist and Aurist to the Milwaukee and the County Hospitals. MILWAUKEE, WIS.

JAMA. 1901;XXXVI(3):177-179. doi:10.1001/jama.1901.52470030033001f

Although we know that our vision very closely depends in its acuity on the degree of illumination, we have not arrived at establishing a definite law as to the relation of sight and intensity of light which might be formulated in mathematical terms. Experiments were made in that direction as early as 1754, by the celebrated astronomer, Tobias Mayer, of Goettingen. He changed the distances of a candle from ½ to 13 feet from certain systems of lines, and ascertained the distances in which he still could see them. From this he calculated the visual angles and found them, that is, the vision, at an inverted ratio to the sixth roots of the intensities of light. One hundred years later Aubert found that vision increases at a little faster rate than the logarithms of the intensities of light. Another method, adopted by Schmidt-Rimpler, Carp and Cohn, was to note the