NATURAL PHILOSOPHY. 101 



ductor of electricity, while a bar of metal is a good conductor, and 

 it still remains to be proved that such a distribution of electricity as 

 that we have described relative to the bar of metal can be produced 

 in a column of air. 



The foregoing are the principal hypotheses which have been ad- 

 vanced to account for what has been considered the free electri- 

 city of the atmosphere. After an attentive study of the whole subject, 

 we have been obliged to reject them all as insufficient, and com- 

 pelled, in the present state of science, to adopt the only conclusion 

 which appears to offer a logical explanation of all the phenomena, 

 namely, that of Peltier, which refers them not to the excitement of 

 the air, but to the inductive action of the earth primarily electrified. 



The author of this theory, we are sorry to say, did not receive that 

 attention which his merits demanded, nor his theory that considera- 

 tion to which so logical and so fruitful a generalization was justly en- 

 titled. 



Peltier commenced the cultivation of science late in life, and, since 

 the untutored mind of the individual, like that of the race, passes 

 through a series of obscure and complex imaginings before it arrives 

 at clear and definite conceptions of truth, it is not surprising that his 

 first publications were of a character to command little attention, 01^ 

 indeed, to excite prejudice, on account of their apparent indefinite 

 character and their want of conformity with established principles. 

 His theory of atmospheric electricity requires to be translated into 

 the ordinary language of science before it can be readily compre- 

 hended, even by those best acquainted with the subject, and hence 

 his want of appreciation may be attributed more to the peculiarities 

 of the individual than to the fault of the directors of the science of 

 the French Academy. 



According to the theory of Peltier, the electrical phenomena of the 

 atmosphere are entirely due to the induction of the earth, which is 

 constantly negative, or what, in the theory of Du Fay, is called res- 

 inous. He offers no explanation, as far as we know, of this condition 

 of the earth, which, at first sight, would appear startling, but, on a 

 little reflection, is not found wanting in analogy to support it. The 

 earth is a great magnet, and possesses magnetic polarity in some re- 

 spects similar to that which is exhibited in the case of an ordinary 

 loadstone or artificial magnet. This magnetism, however, is of an 

 unstable character, and is subjected to variations in the intensity and 

 in the direction of its polar force. In like manner we may consider 

 the earth as an immense prime conductor negatively charged with 

 electricity, though its condition in this respect may, like that of its 

 magnetical state, be subject to local variations of intensity, and per- 

 haps to general as well as partial disturbance. It may be said that 

 this merely removes the difficulty of the origin of the electricity of 

 the atmosphere to an unexplained cosmical condition of the earth, but 

 even this must be considered an important step in the progress of 

 scientific investigation. The hypothesis of Peltier has, since his 

 death, been rendered still more probable by the labors of Sabin, 

 Lloyd, La Mont, Bache, and others, in regard to certain perturba- 

 tions of the magnetism of the earth, which are clearly referable to 

 the sun and moon. It must now be admitted that magnetism is not 



