28 On the Depth and Saltness of the Ocean. 



is 4600 fathoms, or 27,600 feet ; no bottom was obtained ; this 

 was the result of an experiment by Captain Sir J.Clarke Ross, 

 in lat. 15^ S., and 23° W. long. Several experiments have been 

 made at other points, and some with success, bottom being ob- 

 tained in apparent mid-ocean, in between 12,000 and 18,000 

 feet. The ocean has been penetrated in too few places to 

 afford any satisfactory or decisive results upon so interesting 

 a subject; and considering the vast space of our globe occupied 

 by the great ocean, it cannot but strike every one what a 

 wide field is open for investigation and experiment, and how 

 many interesting geological results may be elicited and are 

 connected with these experiments ; sufficient facts have been 

 developed, to prove that the inequalities of the level of the 

 ocean's bed are much more remarkable than those of the 

 land. 



It may excite sui-prise, that we should know so little on 

 this point. Navigators, to whom this interesting inquiry 

 properly belongs, have troubled themselves little about it, 

 unless it was in some way connected with the safety of their 

 voyages. The existence of discoloured water has alone in- 

 duced them to cast the deep-sea lead. There is, however, 

 some excuse to be made ; for though in theory the depth is 

 easily to be ai-rived at, yet to obtain it practically is exceed- 

 ingly troublesome, requiring much time as well as favourable 

 opportunities. 



The mode still practised is the ordinary lead-line. Sub- 

 stitutes for this have been attempted ; many of them are in- 

 genious, and some useful, but they do not obviate the diffi- 

 culties, although they give greater accuracy in the results. 

 Few are aware, that it requires from two to three hours for 

 a well-appointed vessel to make a sounding to the depth of 

 1500, or 2000 fathoms, for which opportunities seldom occur ; 

 calms, or light winds, and a smooth sea, are requisite. 



The mode of sounding practised of late by several British 

 officers to obtain the actual depth, is by attaching a weight 

 of several hundred pounds to a small cord or spun yarn 

 wound on a reel, which is carried off as the weight descends ; 

 on reaching the bottom it is pulled taut and the length ascer- 

 tained ; the cord being too weak to lift the weight, both are 



