I 10 THE SCIENTIFIC PAPERS OF 



could obtain. The motion of a vessel had the effect of washing- 

 off the chloride of copper and magnesia which formed upon the 

 metal. So that although copper sheathing on ships which were 

 kept in motion did not last longer than from 5 years to 7 years, yet in 

 the case of vessels at rest, copper sheathing had been known to last 

 as long as 20 years. In the case of a cable lying tranquilly at the 

 bottom of the ocean, still greater durability might be calculated 

 upon. The copper ordinarily used for ships' sheathing was by no 

 means the most durable that could be obtained. Dr. Percy had 

 found that a small proportion of phosphorus put into the copper 

 had the effect of making it less soluble in sea water than pure 

 copper, and that result was corroborated by his own experiments. 

 Mr. Siemens proposed to use a compound of that character. Small 

 admixtures of silver, or tin, appeared to have the same effect, and 

 it was possible that an alloy of that character might be applied, 

 with equal or greater advantage. 



In the discussion of the Paper 



" ON THE TELEGRAPH TO INDIA, AND ITS EXTEN- 

 SION TO AUSTRALIA AND CHINA," 



By Sir CHARLES TILSTON BRIGHT, M.P., M. Inst. C.E. 



MR. C. W. SIEMENS * said, the author had well described the 

 construction of this cable, and some of the difficulties that had 

 been met with in submerging and working it. With regard to the 

 difficulties in the transmission of messages through Turkey and 

 India, it was to be borne in mind that in India, nearly all the 

 lines were made without insulators in the first instance, the line- 

 wires having been suspended from wooden cross pieces fastened to 

 the poles, and afterwards insulators of unsuitable and untried 

 forms were used. No wonder, then, that the lines should be in a 

 bad condition, independently of the other reason given that the 

 staff was wholly inadequate to the business. He considered that, 

 electrically, the Persian Gulf cable was well adapted to its purpose, 



* Excerpt Minutes of Proceedings of the Institution of Civil Engineers, Vol. 

 XXV. Sessions 1865-1866, pp. 18, 19, 62. 



