.S7A' WILLIAM .sVAJ/A.Y.s, /./ 349 



in order to obtain a smooth working ; and he had proposed to tin 

 tin- inside of the pipes, hut that had to he negatived because it 

 \vould have been too costly. He should have been glad of the 

 opportunity of comparing the estimates of the two descriptions of 

 pipe, believing, as he did, that one would cost several times as 

 much as the other. Another objection raised in the paper against 

 the circuit system had been that time was lost at the inter- 

 mvdiate stations. He did not, however, see the force of that ob- 

 jection. It was very important that the time of transit from 

 the central station to the extreme end of the system should be 

 as short as possible ; but there could be no practical object in 

 shortening the times of transit to the intermediate stations. He 

 would take the case of the second continuous circuit established 

 in London. It had been stated that, in working the circuit 

 from the central station to Cannon Street and Thames Street 

 continuously, the time of transit from the central station to 

 Cannon Street was sixteen seconds more than when the latter was 

 worked as a terminal station, the times of transit being seventy- 

 two and fifty-six seconds respectively. That might be so ; but he 

 thought it was rather an advantage than otherwise to retard the 

 flow in so short a tube, and the intermediate station in Cannon 

 Street did not in any way diminish the speed of the flow from the 

 central station to Thames Street. If the two were worked as 

 separate continuous circuits, more than double the air would be 

 consumed as compared with that required to work the three 

 stations on the circuit system. If it were so desirable to diminish 

 the time of transit, it would be much better to increase the diameter 

 of the pipe. In that case there would be an advantage for both 

 stations in point of speed and working capacity, and engine 

 power would at the same time be saved. He thought, therefore, 

 that the objection raised against the intermediate station did not 

 hold good. Another objection was that the iron pipe caused more 

 friction than the lead tubes. No doubt there was a little more 

 friction to the carrier ; but, seeing that this constituted a very 

 slight amount in the total friction of the transit of air through the 

 pipe, it was not a serious matter, and could have been avoided if 

 the inside of the iron tube were simply covered with a soft metal. 

 He had certain objections to make to the theoretical part of the 

 paper. The authors started with Zeuner's formula?, expressing 



