Prof. W. A. Norton on Terrestrial Magnetism. 3 
explicable manner the intensity of the magnetism of the terres- 
trial particles; or as bearing towards it the relation of cause an 
effect. But there is another view to be taken of the matter. 
We may regard the two principles of heat and magnetism as 
similar in their ultimate physical nature, as every where subsist- 
ing together, and that the causes which produce a variation of 
temperature at the surface of the earth, as we pass from one point 
light, heat and electricity, differing in time and intensity, and pos- 
sibly in some instances in direction, of vibration. Agreeably to 
needle, are subject to the action of the magnetic force of the earth, * 
is evident from the fact that the directive force of the needle is 
Proportional to its mass. Why it is that magnets alone are sensi- 
bly influenced by the impulsive actions of the ethereal pulses, I 
cannot now stop to consider. These theoretical views, I do not 
