EASTING OF THE TKADE- WINDS, ETC. 173 



leading across the calm places. That celebrated microscopist 

 reports that he found South American infusoria in the blood- 

 rains and sea-dust of the Cape Verd Islands, Lyons, Genoa, and 

 other places (§ 325) ; thus confirming, as far as such evidence 

 can, the indications of our observations, and increasing the pro- 

 bability that the general course of atmospherical circulation is 

 in conformity with the suggestions of the facts gathered from the 

 sea as I had interpreted them, viz., that the trade-winds of the 

 southern hemisphere, after arriving at the belt of equatorial 

 calms, ascend and continue in their course towards the calms of 

 Cancer as an upper current from the south-west, and that after 

 passing this zone of calms, they are felt on the surface as the 

 prevailing south-w^est winds of the extra-tropical parts of our 

 hemisphere; and that for the most part, they bring their 

 moisture with them from the trade-wind regions of the opposite 

 hemisphere. I have marked on Plate VII. the supposed track 

 of the " Passat-Staub," showing where it was taken up in South 

 America, as at P P, and where it was found, as at S S ; the part 

 of the line in dots denoting where it was in the upper current, 

 and the unbroken line where it w^as wafted by a surface current; 

 also on the same plate is designated the part of the South Pacific 

 in which the vapour-springs for the Mississippi rains are sup- 

 posed to be. The hands (c^) point out the direction of the 

 wind. Where the shading is light the vapour is supposed to be 

 carried by an upper current. Such is the character of the cir- 

 cumstantial evidence which induced me to suspect that some 

 agent, whose office in the grand S3^stem of atmospherical circula- 

 tion is neither understood nor recognized, was at work in these 

 calm belts and other places. It may be electrical, or it may be 

 magnetic, or both conjoined. 



359. Quetelefs observations. — The more we study the workings 

 of the atmospherical machinery of our planet, the more are we 

 impressed with the conviction that w^e as yet know very little 

 concerning its secret springs, and the little "governors" here 

 and there which regulate its movements. My excellent friend 

 i\I. Quetelet, the astronomer royal at Brussels, has instituted a 

 most excellent series of observations upon atmospherical elec- 

 tricity. He has shown that there is in the upper regions of the 

 air a great reservoir of positive electricity, which increases as 

 the temperature diminishes. So, too, wdth the magnetism of the 

 oxygen in the upper regions. 



