THE AIR OF THE NEW YORK SUBWAY PRIOR TO 1906.4 
By GEORGE A. SOPER. 
INTRODUCTION. 
The object of this paper is to record some hitherto unpublished facts 
concerning the quality of the air of the New York subway before any 
material change was made in its ventilating arrangements, and to 
seek to explain the essential conditions which controlled it. The 
investigation was made by me in 1905 at the request of the Board of 
Rapid Transit Railroad Commissioners for the city of New York. 
The principal questions investigated related to temperature, hu- 
midity, odor, bacteria, and dust. The conditions found in the sub- 
way were compared with the conditions found in the streets through 
which the subway runs, and occasionally with conditions in other 
places. 
In all, there were about 2,200 chemical analyses of air, 3,000 deter- 
minations of bacteria, and about 400 other analyses in special studies 
of dusts, oils, disinfectants, and other substances. About 50,000 sep- 
arate determinations of temperature and humidity were made prior 
to the adoption of a system for automatically and continuously re- 
cording temperatures throughout the length of the subway and in 
the streets. 
The methods employed in studying the different topics were, for 
the most part, such as had been used in other sanitary and meteoro- 
logical investigations in which a considerable degree of accuracy was 
required. It is not claimed that they would have been the best to 
adopt in a purely scientific research. It was necessary to design them 
for practical as well as accurate use. 
For the most part, the air to be analyzed was collected at an eleva- 
tion of 18 inches to 2 feet above the pavement. This height was 
decided on as the most convenient and suitable, after an attempt had 
been made to collect it at the breathing line. Only by taking sam- 
a Read before the Society of Arts, Boston, November 22, 1906. Abridged, by 
permission, from the Technology Quarterly and Proceedings of the Society of 
Arts, Massachusetts Institute of Technology, Boston, Mass. Vol XxX, No, 15 
March, 1907, pp. 58-118. 
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