CONTENTS. XIX 



answered, 356. — The Kain "Winds in the'Mississippi Valley, 357. — Ehrenberg and 

 his Microscope, 358. — Quetelet's Observations, 359. — At Sea in the southern Hemi- 

 sphere we have the Rule, on Land in the northern the Exception, as to the general 

 Circulation of the Atmosphere, 360. — The magnetic Poles, the Poles of the "Wind 

 and of Cold coincident, 361.— The Barometer in the Wind Bands, 362. — More 

 Atmosphere in the northern than in the southern Hemisphere, 363.^ — A Standard of 

 Comparison for the Barometer at Sea, 364. — South-east Trade-winds having no 

 Moisture traced over into rainless Regions of the northern Hemisphere, 365. — Each 

 Hemisphere receives from the Sun the same amount of Heat, 366. — The northern 

 radiates most, 367. — Another Proof of the Crossings at the calm Belts, 368. — Facts 

 and Pearls, 369 Page 147 



CHAPTEE VIII. 



CUERENTS OF THE SEA. 



Obedient to Order, $ 370.— The Fauna and Flora of the Sea, 371. —Those of southern 

 unlike those of northern Seas, 372. — The Capacity of Water to convey Heat, 373. — 

 Currents of the Sea to be considered in Pairs, 374. — Marine Currents do not, like 

 those on Land, run of Necessity from higher to lower Levels, 375. — The Red Sea 

 Current, 376. — Upper and under currents through Straits explained, 377. — The 

 Mediterranean Current, 378.— The Suez Canal, 379. — Hydrometrical Observations 

 at Sea wanted, 380.— Specific Gravity of Red Sea Water, 381.— Evaporation from, 

 382.— The Mediterranean Currents, 383.— The " Drift" of thePha>nix, 384.— Salt- 

 ness of the Mediterranean, 385.— The Escape of salt and heavy Water by under 

 Currents, 386. — ^Vertical Circulation in the Sea a physical Necessity, 387. — The 

 Bars at the Mouths of the Mississippi an Illustration, 388. — Views of Admiral 

 Smyth and Sir C. Lyell, 389— Currents of the Indian Ocean, 390.— The Black 

 Stream of the Pacific contrasted Mith the Gulf Stream of the Atlantic, 391.— The 

 Lagulhas Current and the Storms of the Cape, 392.— The Currents and Drift of the 

 Indian Ocean, 393. — The ice-bearing Currents from the antarctic Regions, 394. — The 

 Currents of the Pacific— Drift-wood, 395.- The Black Current of the Pacific, like 

 the Gulf Stream, Salter than the adjacent Waters, 396. — The Current of Okotsk, 

 397._Humboldt's Current, 398. — The "desolate" Region, 399.— Polynesian Drift, 

 400. — Equatorial Currents, 401.— The Influence of Rains and Evaporation upon 

 Currents, 402. — Under Currents— Parker's deep-sea Sounding, 403. — the Compres- 

 sibility of "^Vater- Elfect of, in the oceanic Circulation, 404. — Assisted by its Salts, 

 405.— The Origin of Currents, 406. — Currents of the Atlantic, 407.— The St. Roque 

 Current, 408.— The Greenland Current, 409 Page 172 



CHAPTER IX. 



THE SPECIFIC GRAVITY OF THE SEA, AND THE OPEN WATER IN THE ARCTIC OCEAN. 



Interesting physical Inquiries, § 420. — Voyages of Discovery to the North Pole, 421. 

 — The first Suggestions of an open Sea in the Arctic Ocean, 422. — Harpoons — ■ 

 Habits of the Whales, 423. — The under Current into the Arctic Ocean— its Influ- 

 ences, 424. — Indications of a milder Climate, 425. — How the littoral Waters, by 

 being diluted from the Rivers and the Rains, serve as a Mantle for tlie Salter and 

 warmer Sea Water below, 426. — An under Current of warm but salt and heavy 

 AVater, 427. — De Haven's Water Sky, 428. — Dr. Kane, 429. — Under Currents 

 change Temperature slowly, 430. — Solid matter annually drifted out of the polar 

 Basin, 431. — Volume of '^^'ater kept in jMotion by the Arctic Flow and Reflow, 

 432. — The Hj'drometer at Sea, 433. — Specific Gravity of average Sea Water, 434. 

 ■ — An Anomaly, 435. — Influence of the Trade-winds upon the Specific Gravity of 

 Sea Water, 436. — Compensating Influences, 437. — Nicely adjusted, 438. — A 

 thermal Tide, 439. — The isothermal Floor of the Ocean, 440.— Thermal Dilata- 

 tion of the Water, 441.— Experiments on the Freezing Point, 442.— Sea Water at 

 summer more expansible than Sea Water at Winter Temperature, 443. — Data for 

 Plate X., 444. — A thermal Tide: it ebbs and flows once a Year, 445. — Sea Yv^ater 

 of the southern cooler and heavier, Parallel for Parallel, than Sea Water of 



