# Popular Science Monthly/Volume 31/October 1887/Color-Blindness Among Railroad Employees

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* COLOR-BLINDNESS AMONG RAILROAD EMPLOYÉS
By WILLIAM THOMSON, M.D.,
PROFESSOR OF OPHTHALMOLOGY IN THE JEFFERSON MEDICAL COLLEGE OF PHILADELPHIA.
THE conflict between the officers and the employés of the Reading Railroad, with its forty-two thousand employés on three thousand miles of track, which has occupied recently the attention of the public, and has threatened to produce a suspension of work on that road, has reopened the question of color-blindness among railroad employés, and led to a full demonstration of its existence among those engaged even as engine-men, where the defect might lead to serious accidents, with loss of property and life. The officers of the road have selected the system for examination suggested by the writer, and employed to a full success for more than live years past on the Pennsylvania Railroad, and have appointed me to supervise its details, and, as ophthalmological expert, to decide all doubtful cases after careful examination of those found defective by the non-professional examiners of the company.
The conflict is nearly over, since demonstrations of the optical defect in engineers, made before a committee appointed by the employés have satisfied them of the propriety of the testing, and that the safety of the traveling public demands the removal of all color-blind persons from positions where their optical defect might be the cause of distressing accidents. In the recent demonstrations, I was able at my office to show that an engine-man declared a red danger-signal, made by placing red glass in front of a large gas-light at a distance of two feet away, to be a green light; he was also not only unable to distinguish a red from a green flag within six feet, but he failed to classify the flags, white, red, green, and blue, properly, even when allowed to take them in his own hands.
The system adopted by the Reading Railroad is the one in use on the Pennsylvania Railroad, and owes its value to the fact that large bodies of employés can be brought under inspection, and their defects discovered by non-professional examiners. It has been fully described in the "Medical News" of January 14, 1882, in the second edition of Nettleship's work on "Diseases of the Eye," and in a paper read before the American Association for the Advancement of Science, in September, 1884, and in "The Popular Science Monthly" for February, 1885, and to those sources the reader is referred for further information.
Previous to its adoption by the officers and directors of the Pennsylvania Railroad two thousand men were examined, and their blanks ​submitted to me, and the color-blind men sent to my office for final action. Mr. Pugh, General Manager, stated, in September, 1884, that there were thus detected four per cent of men color-blind, and ten per cent of men deficient in acuteness of vision, and that, although it was very difficult to keep accurate notes of all examinations, he was satisfied that all dangerous persons had been removed up to that date, when over twelve thousand employés had been submitted to the system.
The statistics obtained upon the two thousand men were used as the standard by all the Division Superintendents, and, however difficult it might be to report to the central office the full details of their examinations, they were always controlled by these known and accepted ratios. It has not been found requisite to send all men deficient to the ophthalmological expert, since they did not demand it, but submitted to the changes rendered necessary without opposition; hence, I am unable to furnish exact reports of the examinations made at remote portions of the road. Most of the color-blind men have passed under my hands, as well as many cases of astigmatism, optical defects, and diseases or injuries reducing the sight below the standard, and the results may some time be found worthy of publication.
An opportunity to present the last opinions of the officers of the Pennsylvania Railroad has been afforded by a request which was made by the German Government, through its Minister, to the Surgeon-General of the United States Army, for statistical and other information on the subject, and this letter, referred to me by the Surgeon-General, has been answered by Mr. Pugh, who has kindly made efforts to obtain the figures from the great organization of which he is General Manager. He writes, under date of July 7, 1887, and says:
"I regret that so long a time has elapsed since the receipt of yours of May 25th, and this reply. The delay has been occasioned by our efforts to obtain some statistical information, which I regret to find has not been kept up as closely as was intended. I inclose herewith statements showing the number of employés examined during the past five years, with the results stated.
"I can only add that we have attained the most satisfactory results from the system, and I think we can confidently claim that sense of security which follows the belief that we have no one employed in any position in which the use of signals is required, whose color-sense and sense of vision will not enable him to accurately determine all signals by which his action is governed."
| Total number examined on lines east of Erie | 25,158 |
| Color-blind | 481 |
| Defective vision | 661 |
| Hearing | 158 |
I am informed that the system has been found so satisfactory that it has been extended to the lines west of Pittsburg, and no doubt is now in use throughout all the lines controlled by the Pennsylvania ​Railroad, including seven thousand miles of track and one hundred thousand employés.
It will be remembered that this system is also used to prevent the admission of defective men into the service, and that the apparently small percentage of color-blind in this table may be ascribed to the non-application of men who know their deficiency, and to the fact that men in the service knowing their defect would leave the road before examination, and thus escape detection, and be enabled to gain employment on other roads where no examinations are required. Perhaps twelve or thirteen thousand was the number who were subject to examination by virtue of being in positions where color-signals were used to direct them, in 1884, and the difference between that number and the total twenty-five thousand would be made up of new men who would present a small ratio of those below the standard, since men conscious of color-blindness, or poor sight, would not apply.
The fact that the intelligent officers of the Pennsylvania Railroad have adopted this system, purged their old force of all dangerous men, extended its use to all parts of their immense railroad, and now oppose it as a barrier to the admission of men thus unfit for service, is the best evidence that can be adduced to claim for it a successful place among the efforts to render scientific truths of practical value to the world. It is hoped that the Reading Railroad will be sustained in its contest with its employés by the example so quietly conducted by the Pennsylvania Railroad, and that the reform so necessary for the traveling public and for those employés who carry their lives in their hands daily, may be conducted to a happy finish.