468 On Tables of Temperatures of the Sea. [June 18, 



parallel latitudes iu the Atlantic cannot be due to north polar waters, 

 and seems more than could be maintained by local influences, the author 

 concludes that the effect may probably be due to waters from the Antarctic 

 Ocean, of the presence of which the low temperatures at depths throughout 

 the Pacific affords evidence, passing, in the absence of any counter flow, 

 to the extremity of the North Pacific, where they are thrown upwards by 

 the rising slopes of the ocean -bed, as on banks in open oceans. On the 

 other hand, in the South Pacific the conditions seem very similar to those 

 in the South Atlantic. The bathyrnetrical isotherms appear, however, to 

 be prolonged further south than in the South Atlantic, which arises pos- 

 sibly from the circumstance that as none, or comparatively none, of the 

 warm equatorial water can pass into the Arctic Ocean, a larger proportion 

 passes into the Antarctic seas. 



In the Southern and Indian Oceans the conditions seem analogous to 

 those of the North Pacific, only they are more masked by the high surface- 

 temperatures of the Arabian Gulf. 



The author agrees in the opinion which has been advanced of the 

 flow over the ocean-bottom of cold undercurrents at and below 35, one 

 from the north and the other from the south pole to the equator, 

 and of their rise in the equatorial regions of the Atlantic. They 

 must, then, necessarily tend to disperse and escape into other areas ; but 

 whether by a movement in mass of the upper strata, or by currents in 

 more definite channels, or by both causes combined, remains to be proved 

 by further research. He inclines to the latter view. He would suggest 

 the question whether the Gulf-stream, together with others which seem to 

 originate or acquire additional power in equatorial seas, such as the 

 Guinea and Brazilian currents, may not receive either their initial start 

 or be strengthened and maintained by the surging-up of the Arctic 

 and Antarctic waters at the equator, while another portion of those 

 waters may be deflected back in insensible currents to polar regions. 

 In the same way some of the great currents of the North Pacific may 

 arise. 



The paper concludes by a review of the other causes connected with 

 these conditions, by a consideration of the normal isotherms of the polar 

 regions, and by a comparison of the temperatures of inland seas, which 

 are dependent on local climatal conditions, with those of the great oceans, 

 which are subject to such vast distant influences ; and he directs attention 

 to the important bearing which these questions of oceanic physics have 

 on many geological problems. 



