THE CLIMATES OF THE OCEAN. 231 



CHAPTER XIV, 



THE CLIMATES OF THE OCEAN. 



Gulf Stream likened to the Milky Way, <5> 492. — March and September the hottest 

 Months in the Sea, 496. — How the Isothermal Lines move up and down the Ocean, 

 498. — A Line of invariable Temperature, 508. — How the western Half of the At- 

 lantic is heated up, 509. — The Relation between a Shore-line in one part of the 

 World and Climates in another, 512. — The Climate of Patagonia, 516. — The Sum- 

 mer of the northern Hemisphere warmer than the Summer of the southern, indi- 

 cated by the Sea, 521. — How the cold Waters from Davis's Straits press upon the 

 Gulf Stream, 522. — How the different Isotherms travel from North to South wit> 

 the Seasons, 523.— The Polar and Equatorial Drift, 524. 



492. Thermal charts, showing the temperature of the surface 

 of the Atlantic Ocean by actual observ^ations made indiscrimin- 

 ately all over it, and at all times of the year, have been published 

 by the National Observatory. The isothermal lines which these 

 charts enable us to draw% and some of which are traced on Plate 

 IV., afford the navigator and the philosopher much valuable and 

 interesting information touching the circulation of the oceanic wa- 

 ters, including the phenomena of the cold and warm sea currents ; 

 they also cast light upon the climatology of the sea, its hyeto- 

 graphic peculiarities, and the climatic conditions of various regions 

 of the earth ; they show that the profile of the coast-line of inter- 

 tropical America assists to give expression to the mild climate of 

 Southern Europe ; they also increase our knowdedge concerning 

 the Gulf Stream, for it enables us to mark out, for the mariner's 

 guidance, the " Milky Way" in the ocean, the waters of which 

 teem, and sparkle, and glow with life and incipient organisms as 

 they run across the Atlantic. In them are found the clusters and 

 nebulae of the sea which stud and deck the great highway of ships 

 on their voyage between the Old World and the New ; and these 

 lines assist to point out for the navigator their limits and his way. 

 They show this via lactea to have a vibratory motion that calls to 

 mind the graceful wavings of a pennon as it floats gently to the 

 breeze. Indeed, if we imagine the head of the Gulf Stream to be 

 hemmed in by the land in the Straits of Bemini, and to be sta- 

 tionary there, and then liken the tail of the Stream itself to an im- 



