101 



alkali ; want of material, however, prevented him arriving at a satis- 

 factory conclusion on this point. 



3. On the Place of the Poles of the Atmosphere. 

 By Professor C. Piazzi Smyth. 



This was merely a note on some of the recent discoveries and 

 generalizations, by Lieut. Maury, U.S.N., on the motions of the at- 

 mosphere. It had been clearly proved by the extensive researches 

 of Lieut. M.j that the trade-winds when rising at the equator, do 

 not, as previously held, return to their own poles, but cross over to 

 the opposite ones ; and thus traverse the extent of the whole earth 

 from pole to pole, in a curvilinear direction, on account of the effect 

 of the rotation of the earth. The whole atmosphere thus partakes 

 of a general movement, the upper half moving towards the poles, 

 and the lower towards the equator, or vice versa^ according to the 

 latitude of the place ; the former occurring between the parallels of 

 0° and 30°, and the latter between 30° and 90°. At 0° and 30° 

 two nodes, so to speak, of the upper and lower currents take place ; at 

 the former ascending, and indicated by a low barometer ; at the latter 

 descending, and marked by increased barometric pressure. At the 

 point of 90°, the pole, or thereabouts, the revolution of the currents 

 and their change of direction for N. and S., and vice versa, with an- 

 other node, takes place, and marked, Lieut. Maury thought, by a 

 calm region, as the two nodal zones of 0° and 30° most undoubtedly 

 are. 



As to the place of this calm polar point, which we shall probably 

 long want observations to determine, Lieut. Maury did not place it 

 over the poles of rotation of the world, but over the magnetical poles, 

 without, however, as the present author thought, sufficient reason. 

 Indeed, he much lamented that after the admirable developments 

 made by Lieut. Maury of the motions of the atmosphere, he 

 should have thus brought in merely the name of magnetism to clear 

 up one obscure point. Meteorology pursued on the system of strict 

 mechanical and scientific inquiry was now disclosing a most interest- 

 ing and understandable series of phenomena, and promised a legitimate 

 harvest of more. But the history of this science in times past, points 

 to so many occasions when rational trains of observation were impeded 

 by the gratuitous introduction of a magnetic or electric element, and 

 thought to be needless thereafter, that the author supposed that it 

 might be of some service to shew that there was no probability in 



