K =-§ ?c =-^- C .... (64) 



402 Dr. Carpenter on Mr.CrolPs " Crucial-Test " Argument. 

 and the oscillations are then expressed by taking 



Up ~_ __ .Uq 



in (61) and (55). By giving moderately great values to p, 

 q, and p — q, the rigorous solution may be satisfactorily ap- 

 proximated to by easy, methodical, and not very laborious 

 arithmetic. The proof is obvious from § 9 (44). 



17. Corresponding investigations to find solutions for the 

 case of water over one or both poles must be reserved for a 

 future article. They involve highly interesting extensions of 

 Laplace's admirable process referred to in § 9 of the present 

 article and in several places of the last two Numbers of the 

 Philosophical Magazine. 



Yacht ' Lalla Rookh,' 

 Clyde, October 14, 1875. 



XLV. Remarks on Mr. CrolFs " Crucial-Test" Argument. 

 By William B. Carpenter, M.D., LL.D., F.R.S* 



THE confidence with which Mr. Croll asserts, in his recent 

 Papers, that the c Challenger ' Temperature-soundings fur- 

 nish a " crucial test " of the Wind and Gravitation Theories of 

 Oceanic Circulation, is not unlikely to mislead those who suppose 

 that because Mr. Croll is an expert Arithmetician, he is to be 

 equally trusted as an authority in Physics. 



I protest, in the first place, against his putting the two doc- 

 trines in antagonism. I no more believe that the vertical Ther- 

 mal circulation can explain all the facts of Ocean temperature, 

 than that the horizontal Wind circulation is alone competent 

 to account for them. The two circulations are not only compa- 

 tible, but mutually complementary; and as I have so treated 

 them in all that I have written on the subject during the last 

 five years, it is scarcely fair in Mr. Croll to ignore the fact that 

 I have explicitly recognized the modifying influence of the Wind- 

 circulation in the temperature of the North Atlantic, and also in 

 that local peculiarity of the North Pacific surface-temperature to 

 which he specially directs attention as opposed to my views. 

 How the vast and deep basin of the North Pacific comes to be 

 nearly filled with glacial water in any other way than by gravi- 

 tation, Mr. Croll does not attempt to explain. I have clearly 

 proved, by the example of the Mediterranean and the Red Sea, 

 that depth per se has no influence on temperature, and that the 

 deepest water in any locality will not be colder than the iso- 

 cheimal of the locality unless it have flowed thither from a colder 



* Communicated by the Author. 



