The New York Rapid-transit Subway

62 DISCUSSION ON NEW YORK SUBWAY. [Minutes of Col.Yorke. Colonel H. A. Yorke wished to follow the previous speakers in expressing his high appreciation of the cordiality and courtesy with which the Author and his assistants had received him on the occasion of his visits to New York in 1902 and 1905, and to thank them for the trouble which they took to show him all that they were doing in the construction of their great undertaking. It was always a pleasure to Americans to welcome Englishmen, and among no class was that more marked than among American engineers and railway men. Attention had already been directed to certain general features of the work, and more particularly to the bold- ness and originality shown in designing and carrying it out, as well as to the ingenuity with which difficulties had been met and overcome; and he proposed to say a few words on one or two details which were of special interest to himself. Sir John Wolfe Barry had observed that the stresses in the roof girders were high, amounting to as much as 9 tons per square inch. In another part of the Paper Colonel Yorke noticed that the girders which carried the elevated portion of the railway, and which would have to bear the rolling loads of the trains passing over it, were not stressed so much. On p. 24 it would be seen that in the longitudinal girders the stress was limited to about 41 tons, and in the cross girders to 41 to 5-8 tons, per square inch. The Author explained the high stresses in the roof-girders of the subway by saying that a very liberal estimate had been made of the loads that might be brought upon the girders; and probably the Author had also in his mind the point that those loads would only come on the girders at rare intervals : that was to say, the maximum loads for whicli he had provided were the piling-up of materials for building purposes in the streets, or the fall of a building into the street in case of fire, or other special loads of that description. That being so, perhaps it was legitimate to take rather a higher limit of stress for the roof-girders than was usually taken in England. The stresses of the girders of the elevated structure, wliich might be regarded as regular working-stresses, accorded with English practice. The stations seemed to him to be laid out in an admirably convenient manner,and he was particularly glad that the Author had laid great stress on the necessity of having the entrances and exits from a platform situated as nearly as possible in the middle of the length of the platform. That point had come to his own notice on more than one occasion in connection with the plans of the more recently-constructed tube railways in London, in which every effort had been made to keep the exits and entrances as nearly as possible in the middle of the platform. Unfortunately it