I need not remind the members of the Institute that there is danger in the inability to distinguish instantly and accurately the color of the red and green side lights, the colors of signal flags, of buoys, marks, and light-houses. The extent of the danger will of course depend on the number of people having any chromatic defect of vision and how complete this is. Now, although warnings were given as to the frequency of color blindness and its dangers on land and sea as long ago as 1854 it has since then, as before, been regarded by the general community, as, an infrequent, rather scientific curiosity. Its great practical importance on the sea and on railroads has only been brought forward and explained to the community during the last five years, most notably by Prof. Holmgren of Upsala, Sweden. His monograph excited a great deal of attention as soon as it appeared in French and German. A brief translation of it is in the Smithsonian Reports. It is also incorporated in my volume on "Color blindness, its Dangers and Detection," now adopted as a manual for the medical officers of the U. S. Army, Navy, and Marine-Hospital Service.
Synopsis of a Lecture on Color Blindness and its Dangers on the Sea
B. Joy Jeffries, M. D.