Scientific Intelligence — Zoology, 403 



tinued to sweep along at a greatly lower level with the general body 

 of the current, must bring the temperature of the surface-water into 

 nearer correspondence with that below. In low latitudes, the sur- 

 face-water is hotter than that below ; and, accordingly, it is a gene- 

 ■ ral remark, that the temperature water sinks as the water shoals, or 

 oven in passing over hanks whose depth is very considerable. If 

 this theory of the phenomenon be correct, the contrary ought to be 

 observed in situations where the surface-water is colder than that 

 below, as it is known to be, under particular circumstances, in the 

 polar seas." The subject is one of considerable interest to the 

 navigator, as the approach to land or shoal- water is indicated by 

 the thermometer, in many places, with a high degree of sensibility. 

 A remarkable instance of this kind occurs oft' the west coast of 

 Africa, of which an account is given by Sir J. C. Ross.* 



11. Greatest ascertained Depth of the Ocean. — On the 3d of 

 June, when in latitude 15° 3' S., and longitude 23° 14' W., being 

 nearly calm, and the water quite smooth, we tried for, but did not 

 obtain, soundings with 4600 fathoms of line, or 27,600 feet. This 

 is the greatest depth of the ocean that has yet been satisfactorily 

 ascertained, but we have reason to believe that there are many parts 

 of it where it is still deeper. Its determination is another deside- 

 ratum in terrestrial physics of great interest and importance. — Sir 

 James C. Rosses Voyage to the Southern Seas, vol. ii. p. 381. 



12. Height of Waves, — Although the south-westerly breeze of 

 the preceding day hardly amounted to a moderate gale, we found 

 that this morning we had run into a heavy swell from that direction. 

 The result of several experiments gave only twenty-two feet for the 

 entire height of the waves, or eleven feet above and below the gene- 

 ral level of the ocean ; the velocity of the undulations eighty-nine 

 miles per hour, and the interval between each wave nineteen hun- 

 dred and ten feet. — Sir James C. Ross's Voyage to the Southern 

 Seas, vol. i. p. 31. 



ZOOLOGY, 



13. Marine Invertebrata found at great depths in the Ocean. — 

 We got soundings in three hundred fathoms, and the dredge being 

 again put over, and allowed to trail along the bottom for two or 

 three hours, brought up many animals, some corallines, and a 

 quantity of sand, mud, and small stones. Amongst them we found 

 several entirely new forms of creatures, of which accurate drawings 

 were taken by Dr Hooker, which, together with their descriptions, 

 are now in course of publication, and constitute one of the more in- 

 teresting features of our researches. It is well known that marine 

 invertebrate animals are more susceptible of change of temperature 

 than land animals ; indeed, they may be isothermally arranged with 

 great accuracy. It will, however, be difficult to get naturalists and 



* Sir J. C. Boss's Voysge, vol. i., p. 34. 



