THE SEA AND THE AT:5I0SPIIERE. 17 



consisting o± sulphuretted hydrogen gas, hydrochlorate of ammonia, 

 etc., etc., in various quantities and proportions, according to the 

 locality of the specimen. 



49. If we imagine the whole mass of the earth to be divided into 

 Proportion of water 1786 CQual parts bv wcififht, then the weiejht of all 



to the niass of the ., / • n i i t j >■ > 



earth. the watcr m the sea would, according to an estimate 



by Su' John Herschel, be equivalent to one of such parts. Such is 

 the quantity, and such some of the quahties of that dehghtful fluid 

 to which, in the laboratories and workshops of natm^e, such mighty 

 tasks, such important offices, such manifold and multitudinous 

 powers have been assigned. 



50. This volume of w^ater, that outweighs the atmosphere (§1) 

 The three great about 400 timcs, is divided into thi'ee gi'eat oceans, 

 ,.ceans. '" ^}^g Atlaiitic, the Pacific, and the Ai'ctic ; for in the 

 rapid siuTey which in this chapter we are taking of the field before 

 us, the Indian and Pacific oceans may be regarded as one. 



51 . The Atlantic Ocean, with its arms, is supposed to extend 

 'ihe Atlantic, from the Arctic to the Antarctic — perhaps from pole 



to pole ; but, measuring from the icy barrier of the north to that 

 of the south, it is about 9000 miles in length, with a mean breadth 

 of 2700 miles. It covers an area of about 25,000,000 square 

 miles. It hes between the Old World and the Nev\^ : passing 

 beyond the "stormy capes," there is no longer any barrier, but 

 only an imaginary line to separate its waters from that great southern 

 waste in which the tides are cradled. 



52. The young tidal wave, rising in the circumpolar seas of the 

 Its tides. south, rolls thence into the Atlantic, and in 12 hours 



after passing the parallel of Cape Horn, it is foimd pouring its flood 

 into the Bay of Fmidy. 



53. The iltlantic is a deep ocean, and the middle its deepest 

 Its depths. part, therefore the more favourable (§ 13) to the pro- 

 pagation of this wave. 



54. The Atlantic Ocean contrasts very strikingly with the 

 Contrasted with the Pacific. The grcatcst length of one hes east and 

 i'^^'^c- west ; of the other, north and south. The currents 

 of the Pacific are broad and sluggish, those of the Atlantic SAvift 

 and contracted. The Mozambique current, as it is called, has been 

 found by navigators in the South Pacific to be upwards of 1600 

 miles wide — nearly as broad as the Gulf Stream is long. The 

 principal currents'^ in the Atlantic run to and fro between the 

 equator and the Northern Ocean. In the Pacific they rim between 



c 



