THE CLIMATES OF THE OCEAN. 
231 
CHAPTER XIV. 
THE CLIMATES OF THE OCEAN. 
Gulf Stream likened to the Milky Way, § 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, 621. — How the cold Waters from Davis's Straits press upon the 
Gulf Stream, 522. — How the different Isotherms travel from North to South wits' 
the Seasons, 523. — The Polar and Equatorial Drift, 524. ' 
492. Thermal charts, showing the temperature of the surface 
of the Atlantic Ocean by actual observations 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 knowledge concerning 
the Gulf Stream, for it enables us to m.ark 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- 
