154 PHYSICAL aEOaPtAPHY OF THE SEA, AND ITS METEOROLOaY. 



impious to attempt tlie study of its machinery upon any other: 

 toSi'thfphvsl?' theory : it tvas made to he inhaUtecl. How could it 

 cai macbiaery of our be inhabitable but for the sending of the early and 

 studied! ^ the latter rain ? How can the rain be sent except by 

 the winds ? and how can the fickle ^Tuds do their errands miless 

 they have a guide ? Suppose a new piece of human mechanism 

 were shown to one of us, and we were told the object of it was to 

 measure time ; now, if we should seek to examine it with the view 

 to understand its construction, would we not set out upon the 

 principle — the theory — that it was made to measure time ? By 

 proceeding on any other supposition or theory we should be infal- 

 libly led into error. And so it is with the physical machinery of 

 the world. The theory upon which this vfork is conducted is that 

 the earth ivas made for man ; and I submit that no part of the 

 machinery by which it is maintained in a condition fit for him is 

 left to chance, any more than the bit of mechanism by which man 

 measures time is left to go by chance. 



352. That I might study to better advantage the workuigs of 

 Division into wind the atmosphcrical machinery in certain aspects, I 

 ^^^^- divided the sea into bands or belts 5° of latitude in 



breadth, and stretching east and west entirely around the earth, 

 but skipping over the land. There are twelve of these bands on 

 ^ch side of the equator that are traversed more or less frequently 

 by om' fleet of observers ; they extend to the parallel of 60^ in each 

 hemisphere. To determine the force and dnection of the v^ind for 

 each one of these bands, the abstract logs were examined until all 

 the data afforded by 1,159,533 observations were obtained ; and 

 the mean direction of the wind for each of the fom' quarters in 

 every band was ascertained. Considering difierence of temperatm^e 

 between these various bands to be one of the chief causes of move- 

 ment in the atmosphere ; — that the extremes on one hand are near 

 the equator, and on the other about the poles ; — considering that 

 the tendency of every wind (§ 234) is to blow along the arc of a 

 great circle, and that consequently every wind that was observed in 

 any one of these bands must have moved m a path crossing these 

 bands more or less obliquely, and that therefore the general move- 

 ments in the atmosphere might be classed accordingly, as mnds 

 either with northing or with southing in them. We have so classed 

 them ; and we have so classed them that we might study to more 

 advantage the general movements of the great atmospherical ma- 

 chinery. See Plate XV. 



