The New York Rapid-transit Subway

124 CORRESPONDENCE ON NEW YORK SUBWAY. Minutes of Dr. Soper, invited by the Board of Rapid Transit Railroad Commissioners to make a careful study of the whole question in order to discover whether any injurious conditions existed, and if so, how to get rid of them. The investigation extended over about 18 months and was divided into two periods. The first, which might be called the analytical part, extended over the 6 months from June, 1905 to January, 1906. In this period about 50,000 determinations of temperature and humidity were made, and finally a system of automatic thermometric records was established. About 2,000 samples of air were collected and analysed for carbon dioxide and oxygen. About 3,000 bacteriological examinations were made. Microscopic examinations were made of the dust whicli settled from the air, and, by a special device, the weight of dust in a given volume of air was determined. Careful studies were made of the force and direction of the air-currents set up by the moving trains. The utility of large fans was studied at several points in the subway where fans were installed for experimental purposes. The effects of the processes of cleaning employed by the operating company were also critically examined. Numerous special experiments were made, as, for example, the determination of the efficiency of certain chemical disinfectants, the effects of oil on bacteria and the longevity of pathogenic bacteria under subway conditions. Two condensed official reports were made on this first part of the investigation.1 The second period of the investigation began in March, 1906, and ended in March, 1907. The object of the second part was to determine, by examining the physiological condi- tion of the people who worked in the subway, whether any injury was being done to health. The time during which the subway had been in service was too short for any evil effects to be plainly visible, but it was thought desirable to undertake the inquiry at this early date in order to discover impending dangers, if any existed. The work involved a minute study of the physiological condition of one hundred subway employees, all of whom had been engaged in subway work for at least a year. The bodies of employees who happened to be killed during the course of the investigation were autopsied. In order to determine the physiological condition of average men of similar social condition to the subway employees, but engaged in other occupations, 200 men from various walks of life were examined. After the completion of the second part of the investigation, Dr. Soper was requested by the Interborough Rapid 1 See the Annual Reports of the Rapid Transit Commission, 1905, pp. 142-147 and 1906, pp. 210-232.