401 Prof. A. Stoletow on the Absolute Value of the 



by him in Kotzebue's second voyage (1823-26) . It was accepted 

 by Pouillet ancVArago ; and, though put aside for the doctrine 

 of a uniform Deep-sea temperature of 39°, supposed to have been 

 established by the observations of D'Urvilleand Sir James Ross, 

 it was finally accepted explicitly by Sir John Herschel. Sir G. 

 Airy, in his Presidential Address for 1872, spoke of it as "certain 

 in theory and supported by observation." And Sir William 

 Thomson, who has kindly allowed me on various occasions to 

 appeal to his profound mastery of the subject as a test of the 

 correctness of my own conclusions, most emphatically stated in 

 the Geographical Section at Bristol, after hearing Mr. Croll's 

 Paper and my reply to it, that the doctrine " is not a matter of 

 argument, but of irrefragable demonstration." 



On these grounds, therefore, I venture to ask for an " arrest 

 of judgment" in regard to the value of Mr. Croll's " crucial test." 

 Until indorsed by some competent physical authority, I submit that 

 it rests on no better basis than his own inadmissible assumption, 

 which, as can be easily shown (see ( Nature/ Oct. 21), would 

 make the demonstrated inward underflow of iEgean water in the 

 Dardanelles as complete an impossibility as he asserts the Ther- 

 mal Oceanic circulation to be. 



It is satisfactory, however, to learn from Mr. Croll's last com- 

 munication to ' Nature ' (Oct. 7, 1875), that he now allows phy- 

 sicists to have an opinion of their own in regard to the sufficiency 

 of differences of Oceanic temperature to produce circulation. 

 And I am not without hope, therefore, that he may come in time 

 to admit physicists to be in the right on a question which they 

 alone are competent to decide. If I had not found my own views 

 to be indorsed by their assent, I should have at once aban- 

 doned them. 



XLVI. On Kohlrausoh's Determination of the Absolute Value of 

 the Siemens Mercury Unit of Electrical Resistance. By Pro- 

 fessor A. Stoletow. 



To the Editors of the Philosophical Magazine and Journal. 



University of Moscow, 

 Gentlemen, October! (13), 1875. 



N a Note recently published in your Magazine (September 

 1875), Mr. II. A. Rowland points qut an error in Kohl- 

 rausch's determination of the Siemens unit of resistance, and 

 expects that it will account for the difference between Kohl- 

 rausch's result and that of theCommittee on Electrical Standards. 

 The correction, arising from self-induction of the circuit in 

 Kohlrausch's experiments, does indeed tend to reconcile the two. 



