Page:Popular Science Monthly Volume 26.djvu/452

436

January 19, 1883.

James A. Morris, aged twenty-two, employed as Locomotive Fireman, Applicant for

and intensity, and the degree of color-defect measured by means of the ratios that exist between the sizes of the openings transmitting the colored light and the distances at which the man may be placed; the small opening which should be seen by the normal eye at five metres distant, is in diameter one millimetre, while the largest, twenty millimetres, when used at live metres, if not recognized, shows $1/20$ of