r 
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 ; arid 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 own 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. 
