354 THE SCIENTIFIC PAPERS OF 



complaint nor inconvenience in the working. Mr. Preece further 

 stated that the cost of the iron pipes, in connection with the 

 circuit system as established in London, was at any rate higher 

 than the cost of the system of tubes advocated by the Engineers 

 at the Post Office, and that his (Dr. Siemens's) firm charged for 

 the iron pipe at the rate of 15s. per yard, whereas another 

 contractor had laid lead pipes at a rate of ] 3s. 8d. He would 

 not dispute those figures, but Mr. Preece had fallen into the error 

 of making, no doubt unintentionally, a very unfair comparison. 

 In the first place, he compared a 3-inch tube with a tube much 

 less in diameter ; he was not quite certain whether it was a l|-inch 

 or a 2j-inch tube that he referred to as having been laid for 

 13s. Sd. He also compared a mere tube which had been laid in 

 connection with an established apparatus, with the system of tubes 

 and instruments, carriers and other matters, required to constitute 

 a complete circuit system. In the one case the instruments, 

 carriers, and station fittings were not included in the estimate, and 

 in the other they were included. There were also to be added in 

 the case of the circuit system the engineering and general expenses 

 which fell upon his firm in designing, making, and laying down 

 the new system in London. He was employed as Engineer of the 

 Post Office in designing not only the tube, but also the engines,, 

 boilers, reservoirs, and pumping machinery to work the system, 

 and the contracts were let to three firms : Messrs. Easton and 

 Amos, who made the engines and pumping apparatus ; Messrs. 

 Aird, who laid the tubes and completed the earthworks ; and 

 Messrs. Siemens Brothers, who made the other mechanical arrange- 

 ments. It should also be stated that as the system had been 

 matured by his firm at great expense, and patented, they had a 

 perfect right to superadd to their cost a reasonable amount for 

 patent right. Including all the charges the Post Office paid for 

 the first circuit the sum of 5,212, which was at the rate of 

 15s. per yard ; but of this sum 2,900 were paid for the tube and 

 the earthwork, including Mr. Aird's profit on the latter, all the 

 rest being taken up by other work. Thus the figures for com- 

 parison were 8s. 4rf. per yard for a 3-inch iron pipe, as against 

 13s. Sd. per yard for a lead tube of about half that area, which 

 figures fully justified, he thought, his former argument. Mr. Preece 

 likewise stated, that although the continuous or circuit system of 



