176 On- the Question of the Unit of Electrical Resistance. 



Dr. Siemens also speaks of his methods, read to the British 

 Association in 1860, as forming the foundation of the rational 

 system of cable-testing now in use. When writing of what is done 

 in a foreign country, we are often very imperfectly informed as 

 to the literature and progress of that country. I cannot doubt 

 Dr. Siemens never heard of Professor Thomson's lecture or of 

 my papers, or he would in 1860 have mentioned them. 



It is equally clear that he has not paid much attention to the 

 mass of evidence given in 1859 before the Board-of-Trade Com- 

 mittee on submarine cables. I have no doubt that he never 

 heard of Professor Thomson's paper published in 1860 in the 

 Encyclopedia Britannica, giving all the methods which he claims. 

 If he had seen any of these papers, he never could have thought 

 that he had taught us much by a paper in 1860. The methods de- 

 scribed in his interesting paper were quite familiar to Professor 

 Thomson, Latimer Clark, C. F. Varley, myself, and others. The 

 methods are so treated by Professor Thomson in the above article, 

 which deserves to be better known even in England than it is. 



Can Dr. Siemens still think that I avoided mention of all 

 these papers, familiar as they are to me, in order wilfully to be 

 silent as to his work ? 



Be it well understood that I am making no counter accusa- 

 tion of unfairness. I am sure some of the papers I have re- 

 ferred to were unknown to Dr. Siemens ; and probably, with 

 reference to the Report of the Committee of the Board of Trade, 

 as it was only published in 1861, Dr. Siemens may not have 

 observed that the evidence to which I refer was given in 1859. 



I can well understand that Dr. Siemens, who has undoubtedly 

 invented these methods independently and has carried them out 

 successfully in important works by a large and able staff, may not 

 have been fully informed as to the progress independently made 

 in England; but to one who is familiar with the papers referred to, 

 his claim to have founded the rational system now in use reads 

 a little strangely. I will not be led into a controversy as to 

 every little improvement in arrangements, or every mathemati- 

 cal formula in use : these improvements are often made inde- 

 pendently by many men ; and the formula? are often obvious and 

 necessary deductions from perfectly well known principles : but 

 I do claim for Professor Thomson the honour of having been the 

 first to insist on a measurement of the conducting-power of the 

 copper in submarine cables, and to express the quality of the 

 insulation in terms of resistance, though I said nothing of these 

 things in my Royal-Society Report because they were irrelevant. 



I wish in conclusion to say that I believe no English electri- 

 cian is more fully persuaded of the great services rendered to 

 telegraphy by Dr. Siemens than I am. I know the immense 



