Dr. Williams' remarks leave but little to be said in favor of the use of a lantern for examination of the color sense. In the system in use of the Pennsylvania Railroad the lantern of Donders has been advised for the testing by the ophthalmic expert, but I am now convinced that a test of this kind should be used in conjunction with the colored wool stick by all the examiners who act under the direction of the division superintendent. Two-fifths of the time of a railway employee's life is spent in governing his action by colored lights by night. The lantern furnishes the test. It also gives us the means of detection of central scotomata, or the color defects caused by central amblyopia induced by tobacco and alcohol. It consists of a small kerosene lamp, or spring candle-stick on which can be placed an asbestos chimney seven inches in
THOMSON W. IMPROVED METHOD OF TESTING COLOR PERCEPTION.. JAMA. 1900;XXXV(11):675–676. doi:10.1001/jama.1900.24620370017001f
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