176 Professor C. Piazzi Smyth's Meteorological 



non, namely, the lower temperature of the southern hemi- 

 sphere to the northern. 



Secondly f Lieut. Maury brings forward another proof of 

 a more exact nature, and very satisfactory as far as it goes, 

 namely, an independent discovery of Ehrenberg's, that a 

 peculiar red rain on the coast of Barbary, the Canaries, and 

 -Spain, contained South American infusoria ; for, according to 

 this new idea of the general motion of the atmosphere, the 

 rain winds of the above named countries should, when ga- 

 thering their supplies, have passed over the latter mentioned 

 continent. 



So far exceedingly good, and we only require more facts of 

 the same description, more carefully inquired into, and more 

 fully published, to prove the case; and then will come the grand 

 question, as to the cause of these phenomena. This Lieut. 

 Maury has attempted, but not so successfully : he professes 

 to see an explanation of it in Faraday's discovery of the mag- 

 netical quality of oxygen gas, but he does not explain how, 

 and it is not at all likely that any magnetic element in the 

 atmosphere could, by such virtue, exercise the prodigious 

 mechanical force required to set and keep in motion the 

 whole air: though it is likely enough that, on the other 

 hand, the atmosphere having its movements from mechani- 

 cal and thermotic causes, may, in coursing over the earth 

 from pole to pole induce magnetic currents having the feeble 

 intensity found to exist in terrestrial magnetism. We can- 

 not, however, but think that Lieut. Maury has, on the whole, 

 opened up a most important question, has placed the subject 

 in a grander light than it was ever viewed in before, and it 

 is to be hoped will be the means of a greater amount of at- 

 tention, with increased instrumental means, and more ac- 

 curate methods being devoted to the inquiry. 



The Rotation of the Earth. — Though no reasonable man 

 now doubts the earth's rotation on its axis, yet some crucial 

 experiment, by which it should be undeniably exhibited with- 

 in the four walls of a room, has long been felt to be a desi- 

 deratum of some little importance, to complete at least the 

 educational means commanded in the present day, and through 

 which we are now enabled so easily to pass through all those 



