CONTENTS. xix 



mense Body of warm Water drifting South, 268. — Currents about tlie Equator, 

 270. — Under Currents : Experiments of Lieutenants Walsh and Lee, 271. — 

 Proof of under Currents aftbrded by Deep Sea Soundings, 272. — Currents caused 

 by Changes in Specific Gravity of Sea Water, 273. — Constituents of Sea Water 

 every where the same ; affords Evidence of a system of Oceanic Circulation, 274 — 

 Currents of the Atlantic : The great Equatorial Current : its Fountain-head, 

 275. — The Cape St. Roque Current proved to be not a constant Current, 276.— 

 Difficulties of understanding all the Currents of the Sea-shore of the Atlantic can 

 not be accounted for without the aid of under Currents, 277 Page 124 



CHAPTER VIL 



THE OPEN SEA IN THE ARCTIC OCEAN. 



How Whales struck on the east Side of the Continent have been taken ozi the west 

 Side, ^ 278. — Right Whales can not cross the Equator, 279. — How the Existence 

 of a northwest Passage was proved by the Whales, 280. — Other Evidence in F^ivor 

 of it, 281. — An under Current sets into the Arctic Ocean, 282. — Evidences of a 

 milder Climate near the Pole, 284. — The Water Sky of Lieutenant De Haven, 285. 

 — Tliis open Sea not permanently in one Place, 286 14G 



CHAPTER VHL 



the salts of the sea. 



What the Salt in the Sea Water has to do with the Currents in the Ocean, <^ 289. — 

 Reasons for supposing the Sea to have its system of Circulation, 290. — Arguments 

 furnished by Coral Islands, 293. — What would be the Effect of no system of Cir- 

 culation for Sea Water 1 295. — Its Components, 297. — The principal Agents from 

 which Dynamical Force in the Sea is derived, 300. — Illustration, 302. — Sea and 

 Fresh AVater have different Laws of Expansion, 308. — The Gulf Stream could not 

 exist in a Sea of fresh Water, 309. — The effect of Evaporation in producing Cur- 

 rents, 310.— How the Polar Sea is supplied with Salt, 323.— The Influence of this 

 under Current upon open AVater in the Frozen Ocean, 326. — Sea Shells : The 

 Influence exerted by them upon Currents, 330. — Order among them, 335. — They 

 assist in regulating Climates, 336. — How Sea Shells and Salts act as Compensa- 

 tions in the Machinery by which Oceanic Circulation is conducted, 339. — Whence 

 come the Salts of the Sea 1 344 150 



CHAPTER IX, 



the equatorial cloud-rixg. 



Description of the Equatorial Doldrums, ^ 346. — Oppressive Weather, 348. — The Of- 

 fices performed by Clouds in the terrestrial Economy, 349. — The Barometer and 

 Thermometer under the Cloud-ring, 350. — Its Offices, 353. — How its Vapors are 

 brought by die Trade- Winds, 361. — Breadth of the Cloud-ring, 363. — How it 

 would appear if seen from one of the Planets, 364. — Observations at Sea interest- 

 ing, 368 171 



