296 Annual Report. 



The Council has before remarked the importance of these- 

 observations every where, and especially in our situation. If 

 we conceive a sheet of definite and nearly constant breadth, 

 stretched over and accommodated to the surface of the globe, 

 and extending from our neighbourhood beyond the Equator, 

 we shall represent the space subject to the influence of the 

 trade winds. While its boundaries continue nearly con- 

 stant, it shifts its position, coming south, and including 

 in it our atmosphere in summer, and departin^j from us in 

 ■winter. Hence, obviously, arises the general character of 

 these seasons. It remains to be determined, what are its pre- 

 cise boundaries during ditferent periods of the year, or how far 

 south from us does the trade wind commence in summer, and 

 how far north of us is found its first stir in winter. It cannot 

 be expected its bounds are not accommodated to the parallels 

 of latitude, and to the isothermal parallels, but is likely to bear 

 a closer relationship to the latter. Not only the outline but 

 probably the depth or altitude of the current would present 

 great irregularities, if a section of it, nearly corresponding to 

 the latitude, could be produced : and along the portions where 

 the lower current is thinnest or shallowest, we may expect the 

 returning aerial stream from the Equator running as it were in 

 grooves or channels, and sooner coming to impinge upon the 

 surface of the ground: such streams of the great movement, 

 would evidently bend round to follow and rejoin the South- 

 Easter in its voyage to the Tropic. This is probably the cha- 

 racter and course of the South-West winds, which occasionally 

 prevail here at all seasons. Local circumstances also of diflerent 

 characters may occasionally project a portion of one current 

 upon or through the other, and produce variations in duration 

 and intensity in the breeze. Such circumstances may have the 

 effect of not only inclining the direction of the current from 

 its proper angle with the meridian, but also for short spaces 

 may influence its natural parallelism to the surface, as is ex- 

 emplified in the descending cataract of the South-easter, which 

 sometimes sweeps over and leaves undisturbed the atmosphere 

 of our valley to spend its fury beyond us on the waters of the 

 bay, in ^such circumstances it will naturally be deflected again 

 partially from the surface, and proceed for a little in a set of 

 diminishing rebounds, rendering its squalls local in their in- 

 tensity, until friction and mutual pressure quell the disturbance 

 and force it into the common regularity of the trade wind. 

 We have therefore again to observe the advantage of many 

 and separated points of observation, and the benefit which 

 would be answered from having a map of the districts of the 

 winds for one or many successive days, as might ht attained 

 through means formerly noticed, in the records kept by the 

 numberless vessels navigating the ocean. A request to this 

 effect as to a period of a week or a month, if issued by such a 



