MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 123 



can reconcile a greater number of known facts and phenomena 

 than we can under the supposition that there is no such crossing. 

 The rules of scientific investigation always require us, when we 

 enter the domains of conjecture, to adopt that hypothesis by which 

 the greatest number of known facts and phenomena may be rec- 

 onciled ; and therefore we are entitled to assume that this cross- 

 ing does take place, and to hold fast to the theory so maintaining 

 until it is shown not to be sound. 



231. That the magnetism of the atmosphere is the agent which 

 guides the air across the calm belts, and prevents that which en- 

 ters them from escaping on the side upon which it entered, we 

 can not, of our ow^n knowledge, positively affirm. Suffice it to 

 say, that we recognize in this property of the oxygen of air an 

 agent that, for aught we as yet know to the contrary, may serve 

 as such a guide ; and we do not know of the existence of any 

 other agent in the atmosphere that can perform the offices which 

 the hypothesis requires. Hence the suspicion that magnetism and 

 electricity are among the forces concerned in the circulation of the 

 atmosphere. 



