210 Miscellaneous Intelligence. 



45 north latitude, the ocean contains, at the same place, the same 

 quantity of salt, as low at least as 1000 toises. For ascertaining the 

 quantity of salt contained in the water on the surface of the ocean, 

 the observers used hydrometers which, by laying weights on them, 

 were made to sink into the water to a mark on the thin neck of the 

 instrument. It is well known that Dr. Erman has ascertained the 

 contraction of salt water of the specific gravity 1*027 for every de- 

 gree of the thermometer, from 12 R. (59 F.) to 3R. (25J F.), 

 and has proved that such water has no maximum of density, before 

 freezing, like common water. With a view to the investigation here 

 under consideration, the table of Erman was extended, by experi- 

 ments made for the purpose, as far as to 24 R. (86 F.) It was 

 then ascertained that a small difference in the specific gravity of 

 the water had no great influence on the law of contraction by change 

 of temperature, since experiments instituted with this view proved 

 that two portions of water, whose specific gravity was 1*02 and 

 1*03, (between which limits undoubtedly all waters of the ocean are 

 comprehended,) observed nearly the same law, and perfectly so at 

 those temperatures at which observations are made on the ocean. 

 The experiments could be very approximately represented by this 

 expression for the density (rf) of water whose specific gravity 

 = 1*027, arid whose temperature is () degrees of Reaumur's 

 thermometer : 



d~ 1-0-0002053. 2 + 0-0000003723. t*- 0.000000188086. t*. 

 and by this formula the numerous observations of specific gravity of 

 water, in different parts of the ocean, were reduced to the same 

 temperature, viz. 14 R. (63J F.) 



The general result of all the observations is as follows : 



i. The Atlantic Ocean contains more salt than the Pacific 

 Ocean, and the Indian Ocean is, therefore, more salt near the 

 Atlantic than near the Pacific. 



ii. In each of these great oceans there is a northern and a 

 southern maximum of salt ; the northern is farther from the equator 

 than the southern. The minimum is, in the Atlantic, a few degrees 

 north of the equator ; the same is probably the case in the Pacific : 

 there were, however, not sufficient observations to prove it. 



iii. In the Atlantic Ocean the water is more salt to the westward ; 

 there seems to be no such difference in the Pacific. 



iv. The greatest specific gravity of the water in the Atlantic 

 Ocean, at the northern maximum, in lat. 20^ and long. 40 W. of 

 Greenwich, was found to be = T02856 ; that of the Pacific, at the 

 southern maximum, in lat. 17 and long. 119 W. r= 1 -028084. 



v. To the northward of the northern maximum, and to the southward 

 of the southern maximum, the specific gravity of the water conti- 

 nually decreases with the increase of latitude. 



It is clear that the quantity of salt in the water on the surface of 

 the ocean must mainly depend on the evaporation ; and as this de- 



