EASTING OF THE TRADE-WINDS, ETC. 175 



95° 39' west. Neither of these poles is a point susceptible of 

 definite and exact position. The polar calms are no more a point 

 than the equatorial calms are a line ; and, considering that these 

 poles are areas or discs, not points, it is a little curious that phi- 

 losophers in different parts of the world, using different data, 

 and following up investigation each through a separate and in- 

 dependent system of research, and each aiming at the solution of 

 different problems, should nevertheless agree in assigning very 

 neai'ly the same position to them all. Are these three poles 

 grouped together by chance or by some physical cause ? By the 

 latter, undoubtedly. Here, then, we have another of those gos- 

 samer-like clews, that sometimes seem almost palpable enough 

 for the mind, in its happiest mood, to lay hold of, and follow up 

 to the very portals of knowledge, where we pause and linger, 

 fondly hoping that the chambers of hidden things may be thrown 

 open, and that we may be permitted to behold and contemplate 

 the mysteries of the winds, the frost, and the trembling needle. 

 In the polar calms there is (§ 215) an ascent of air; if an ascent, 

 a diminution of pressure and an expansion ; and if expansion, a 

 decrease of temperature. Therefore we have palpably enough a 

 connecting link here between the polar calms and the polar place 

 of maximum cold. Thus we establish a relation between the 

 pole of the winds and the pole of cold, with evident indications 

 that there is also a physical connection between these and the 

 magnetic pole. Here the out-croppings of a relation between 

 magnetism and the circulation of the atmosphere again appear. 



362. The barometer in the wind hands. — Thousands of observa- 

 tions, made by mariners and recorded in their abstract logs, have 

 enabled us to determine approximately the mean height of the 

 barometer for the various bands (§ 352) at sea. Between the 

 parallels of 36° S. and 50° N., Lieut. Andrau, of the Dutch Navy, 

 has collected from the abstract logs at the Meteorological Insti- 

 tute of Utrecht no less than 83,334 observations on the height of 

 the barometer in the following bands. (See table, page 176.) 



363. More atmosphere in the northern than in tJie southern hemi- 

 sphere. — The diagram of the winds (Plate I.) has been con- 

 structed so as to show by its shaded border this unequal 

 distribution of the atmosphere between the two hemispheres. 

 Have we not here proof that the southern hemisphere (§ 261) is 

 indeed the boiler to this mighty atmospherical engine? The 

 aqueous vapour rising from its waste of waters drives the air 



