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Chicago, Ill., August 31, 1898.
To the Editor:
—The importance of railway signals and their correct observation by employes is a matter the subject of which has been given a great deal of study by all railroad officers, to the extent that every conceivable form of signal that genius, talent and mechanism can contrive has been tried and each in turn served the period of its usefulness and relegated to the background, the cruder machine being supplanted by a more perfectly constructed one until today our railway signals are equal in construction to those produced in any country. The medical profession has not kept pace with these mechanical students in their teachings of how to correctly observe these signals and thereby avoid accidents.The average railway surgeon is provided with a few crude tests as to color vision and is taught how to correctly operate them by a superior medical
Hamill JR. Examine Railway Employes' Eyes Periodically and in a Scientific Manner.. JAMA. 1898;XXXI(11):616-617. doi:10.1001/jama.1898.02450110058012