METEOROLOGY. 17 



absence of calorific and mechanical action unless through the medium 

 of chemical action : the obvious incapability of the distant planets to 

 produce any of these effects is conclusive against their asserted share 

 in affecting the weather through the medimn of electric excitation. 

 It is true it has been thought that in the analysis of the sun's light, 

 some of the colours of the spectrum have been more effective than 

 others in exciting electricity ; whether or not this be correct, and which 

 appears from recent investigations very doubtful, the most powerful 

 colours were considered to be indigo, violet, white, and green, whereas 

 the prevailing planetary colours of yellow, orange, and red, were thought 

 to be ineffective. 



In some future number of this magazine an attempt will be 

 made^ to explain some of the causes which may and really do 

 produce changes of the weather ; in the mean time I would conclude 

 the present article with the following observ^ations : — 



Whilst a mean uniformity of distance, and of general influence, ( I 

 use the tenn with reference to a known and demonstrated power) has 

 been maintained in the planetary system from the day of Creation, 

 the investigations of geologists have shewn that this earth has under- 

 gone mutations of temperature and humidity so extensive as no longer 

 to be adapted to the exigencies of the same organic nature; entire genera 

 and species have been swept away, fresh and perfectly distinct 

 successions of animated nature have been from time to time created, 

 and in their turn have been destroyed by the varying and important 

 conditions of the earth and its atmosphere : even the elementary con- 

 stitution of the atmosphere itself has been apparently reconstructed. 

 During the deposition of part of the secondary formation of the earth's 

 surface, it was inhabited by various species of the Saurian or Lizard 

 tribe; from an anatomical and physiological investigation into their 

 structure these reptiles differ essentially from birds, and the mammalia, in 

 the less active performance of the respirator)^ function, and in a lower 

 and simpler structure of the lungs and heart, whereby they become less 

 dependent on the oxygen of the atmosphere for existence. From this 

 and the subsequent extinction of a vast portion of the reptilian class, 

 the physiologist is led to conjecture that the atmosphere had not then 

 undergone those changes which a subsequent consolidation and 

 concentration of certain of its elements may have occasioned. And 

 again, from considerations of the peculiar featmes of the extinct Flora 



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