250 AXXUAL OF SCIENTIFIC DISCOVEEY. 



etable kingdom is made to feed animals, and the animal kingdom, 



^3 ^D 



while containing plant-eaters, demands flesh-eaters for its own bal- 

 ance, for the removal of the dead, and to make out of dead flesh the 

 E roper food for plants, thus to pay its debt to the vegetable kingdom, 

 [ence death pervades the whole system of life in its essence and 

 physical laws; and it could not be prevented in a world of active 

 forces except by a constant miracle ; and this would be an annihilation 

 of nature, that is, of a system of law. Prof. J. D. Dana, Silliman's 

 Journal. 



THE SALTNESS OF THE SEA. 



In the course of the last twenty years the distinguished Danish 

 chemist, Forchhammer, has executed about two hundred complete 

 analyses of water from all parts of the ocean, but in particular from 

 the Atlantic and the north European seas connected with it. At the 

 eighth meeting of the Scandinavian naturalists, at Copenhagen, the 

 important results of these laborious researches were communicated. 



Saltness of the Ocean. The mean of 140 complete analyses gives 

 34.304 of salt in one thousand parts of water, unequally distributed 

 over 16 regions. But the specimens being principally taken at lower 

 latitudes, this mean is too high. If we take 34 in one thousand parts 

 as the mean saltness of the sea at the mean atmospheric pressure, and 

 give the results in differences of ten thousandths from this mean, they 

 will become more perspicuous. 



Thus the mean saltness of the Atlantic (35.77 thousandths) is ex- 

 pressed by -|- 17. 7; of the California Pacific-}- 12.2, Japanese Pacific 

 -j-4.3, Indian Ocean -j- 1.3. The Atlantic system of rivers drains by 

 far the greater portion of the continents, and has the same position in 

 latitude ; thus the evaporation in the Atlantic must be greater than in 

 any other part of the ocean. 



The Atlantic is divided into five regions, viz : 



Keg. III. Arctic region, mean of 16 analyses,-]- 15.6 



" II. North temperate, " " 24 " -4-19.5 



" I. North tropical, " " 14 " -j- 21.7 



" X. South tropical, " " 6 " 4-24.7 



" XL South temperate, " " 6 " -j- 10.4 



" XVI. Antarctic Ocean, " " 1 " 54.4 



Thus the tropical part of the Atlantic is the saltest, and the amount 

 of salt regularly decreases toward the poles ; yet the northern Atlan- 

 tic is more salt than the southern (an influence of the Gulf Stream). 1 



The first great circulation of terrestrial water is represented in 

 these numbers : only a part of the water evaporated between the 

 tropics directly returns to land and sea in form of rain ; another part 

 is carried to the polar regions, here condensed to snow and ice, re- 

 turning toward the equatorial belt either in great fresh-water cur- 

 rents or in veritable ice-streams, thus reestablishing the equilibrium. 



Saltness of Oceanic Currents. The equatorial current has in the 

 Bay of Benin a saltness of-j- 3.8 ; crossing the equator between long. 



1 The maximum of saltness, + 29, or 37.908 thousandths, is in tho north tropical 

 part of the Atlantic, opposite the dry coasts of Sahara, whence hot, dry winds, 

 but uo fresh water may be obtained, lat. 21 13' N. f lon. 23 11' W. 



