202 



Staff Commander T. H. Tizard. [May 10, 



On the reading of my preliminary note I demonstrated by visible 

 experiments many of the points of the theory I have advocated, and 

 which I believe explains all conditions of magnetism, and I propose 

 on the reading of this paper to demonstrate experimentally the 

 remaining evidences. 



II. " Remarks on the Soundings and Temperatures obtained in 

 the Faeroe Channel during the Summer of 1882." By 

 Staff Commander T. H. Tizard, R.N., H.M.S. " Triton/' 

 Communicated by Sir Frederick Evans, K.C.B., F.R.S. 

 Received April 16, 1883. 



[Plates 4-8.] 



Introduction. — The exploration of the Faeroe Channel commenced by 

 H.M.S. "Lightning," in 1868, under the direction of Dr. Carpenter, 

 F.R.S., the late Sir Wyville Thomson, F.R.S., and Mr. Gwyn Jeifreys, 

 F.R.S., at the instance of the Royal Society,* revealed a remarkable 

 pecnliarity, namely, the fact that over one portion of that channel the 

 temperature of the water at the bottom differed 12° to 14° F. from 

 that obtained at similar depths in the other portion, and further 

 investigation by H.M.S. " Porcupine" in 1869 confirmed the observa- 

 tions previously obtained on board the " Lightning." 



The cause of this phenomenon appears to have been unsuspected at 

 the time, but during the voyage of H.M.S. "Challenger" several 

 such peculiarities were observed, though not to such a marked extent, 

 and a theory was formed that where differences of bottom temperature 

 existed at equal depths in adjoining areas those areas would probably 

 be found separated by submarine ridges. 



Viewiug the question on board the "Challenger" from our own 

 observations, combined with those previously obtained in the " Light- 

 ning," "Porcupine," and "Shearwater," and with the advantage of 

 Dr. Carpenter's conclusions on oceanic circulation published in the 

 " Proceedings of the Royal Society " for 1869, it seemed to us reason- 

 able to suppose that in those areas where the minimum temperature 

 was found constant from a given depth to the bottom over an area 

 contiguous to another where the temperature decreased as the depth 

 increased, those areas must be separated by a submarine , ridge, as 

 then the phenomena might be readily explained. For instance, the 

 condition might arise (a) if the minimum temperature was the mean 

 winter temperature of the coldest portion of the separated area, in 

 which case the water at the surface would be flowing in, whilst below 

 it w ould be flowing out over the submarine ridge, as seems to be the 



* See " Proc. Roy. Soc." for 1868. 



