CONTENTS. 



XXI 



Breeze, 321. — Red Fogs in the Mediterranean, 322. — Red Fogs near the Equator, 

 323. — Putting Tallies on the Wind, 324. — They tell of a Crossing at the calm 



Belts 325. Humboldt's Description of the Dust-whirlwinds of the Orinoco, 32G. 



Are the great Deserts Centres of Circulation ? 327. — The Color of "8ea-dust," 



328. A Clew leading into the Chambers of the South, 329. — Red Fogs do not 



always occur at the same Place, but they occur on a northeast and southwest 

 Range 330. — Conditions requisite to the Production of a Sea Fog, 331. — What 

 is the Agent that guides the Air across the calm Belts? 332 Page 127 



CHAPTER VII. 



THE EASTING OF THE TRADE-WINDS, THE CROSSING AT THE CALM BELTS, AND THE 

 MAGNETISM OP THE ATMOSPHERE. 



Halley's Theory not fully confirmed by Observations, § 341.— Observed Course of 

 the Trade-winds, 342. — Velocities of the Trade-winds, 343.— Difference between 

 Observation and Theory, 344.— Faraday's Discovery of Magnetism in the Air, 

 345._Lines of magnetic Force, 34G.— The magnetic Influences of the Oxygen of 

 the Air and of the Spots on the Sun, 347.— The Needle in its diurnal Variations, 

 the Barometer in its Readings, and the Atmosphere in its electrical Tension, all 

 have the same Hours for their Maxima and Minima, 348. — The Question raised 

 by modern Researches, 349.— Wet and diy Air of the calm Belts, 350.— Princi- 

 ples according to which the physical Machinery of our Planet should be studied, 

 351.— Division into Wind-bands, 352.— The medial Bands, 353.— The rainless 

 Regions and the calm Belts, 354.— The Theory of the Crossings restated, and the 

 Facts reconciled by it, 355. — The Question, How can two Currents of Air cross? 

 answered, 356.— The Rain Winds in the Mississippi Valley, 357.— Ehrenberg and 

 his Microscope, 358. — Quetelet's Observations, 359.— At Sea in tho southern 

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

 general Circulation of the Atmosphere, 3G0. — The magnetic Poles, the Poles of 

 the Wind and of Cold coincident, 301. — The Barometer in the Wind Bands, 

 3G2. — More Atmosphere in the northern than in the southern Hemisphere, 363. 

 — A Standard of Comparison for the Barometer at Sea, 364. — Southeast Trade- 

 winds having no Moisture traced over into rainless Regions of the northern Hem- 

 isphere, 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, 369 148 



CHAPTER VHL 



CURRENTS OF THE SEA. 



Obedient to Order, § 370.— The Fauna and Flora of the Sea, 371.— Those of south- 

 ern 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 the 

 Phoenix, 384.— Saltness of the Mediterranean, 385.— The Escape of salt and 

 heavy Water by under Currents, 386. — Vertical Circulation in the Sea a physic- 

 al Necessity, 387.— The Bars at the Mouths of the Mississippi an Ilkistration, 



