PUMPING MACHINERY OF THK WATER AND SEWERAGE BOARD. XL V. 



practical papers as this of Mr. Purniss afford much scope 

 for discussion, and it is to be hoped kindred subjects may 

 be brought forward to keep up interest in the Section. 



After Mr. Furniss had replied, Mr. Selfe apologised for 

 having understood that the Spottiswoode engines were 

 "differential" and for the remarks based upon the mistake. 



Mr. James Shirra said that he had not studied the paper 

 very minutely, but there were a lot of points in the lecture 

 that had not been referred to in the abstract. One thing 

 he wanted to know was, how was the duty of these pumps 

 measured in the tests? Was it determined simply by a 

 consideration of the number of pounds of water lifted and 

 the number of feet it was raised? Duty as arrived at 

 merely by a consideration of the number of foot pounds 

 was not by any means always a true indication of the 

 working power of the pump. Many other things had to Vie 

 taken into consideration. In connection with the figures 

 shown on the diagrams, he would like to know whether the 

 power expended in the suctional column had been put in 

 the head or not? (Mr. Smail, "That was included in the 

 tests by which the figures were arrived at.") Mr. Shirra 

 continuing, said he thought better results would have been 

 achieved in the trials if a pressure gauge had been put in 

 the delivery pipe close to the pump. (Mr. Smail, "That 

 was done.") 



Mr. Selfe, "Was the duty taken from actual pressure?" 



Mr. Smail, "Yes, the pressure due to friction etc., was 

 taken into account as well as the actual weight or volume 

 of water delivered." 



Mr. Shirra, continuing, said that he had noticed in the 

 abstract, that of the three pumps at the Marrickville 

 Stormwater Pumping Station, there were two of local 

 manufacture which were somewhat more efficient than the 



