i84 THE POPULAR SCIENCE MONTHLY. 



absolutely original except certain deductions of my own which, 

 in my opinion, necessarily flow from the assumption that matter 

 is composed of indivisible and indestructible particles. I have 

 reason to believe that these deductions will be received with in- 

 terest and that they Avill throw light on and explain many things 

 which may have puzzled those not intimately acquainted with the 

 subject. 



It may, indeed, be presumed that a popular exposition of the 

 present state of the science of molecular physics will be appreci- 

 ated. Everybody has heard of and knows something about the 

 atomic hypothesis, yet there are few who have been able to follow 

 the more recent researches and speculations of the foremost in- 

 quirers in this difficult department, because they have been com- 

 municated to the world in a manner in which they can only be 

 understood by mathematicians of the highest order. Such master- 

 minds are necessary, and it was perhaps fortunate for mankind 

 that they have hitherto confined themselves more or less exclu- 

 sively to original research, and not frittered away their time by 

 writing popular works ; but it is the duty of humbler intellects to 

 interpret their revelations, and give them the widest possible dis- 

 semination. 



There is, in my opinion, no subject, outside of mathematics, 

 however intricate or abstruse in some of its aspects, which can not 

 be explained in the ordinary language of the people. What can 

 be clearly imagined can also be clearly expressed ; or we might as 

 well carry science and philosophy back to the time of Duns Scotus, 

 when it was considered the greatest triumph of learning to sophis- 

 ticate so profoundly, and hedge around with arguments an obvious 

 absurdity that no ordinary intellect could refute it. 



I would also like to observe that in the manner in which I 

 shall here endeavor to place this subject before my readers I have 

 been largely influenced by the perusal of a recent work on molec- 

 ular dynamics by Lasswitz, a German physicist and philosopher, 

 little known as yet in this country, a profound thinker. To this 

 work, which can not fail to make a great impression on all cultured 

 minds, I am indebted for many of the similes which I intend to 

 make use of. Some of these similes may appear fanciful or ex- 

 travagant, but a little reflection will show their fitness and value 

 in the interpretation of some of the more difiicult problems with 

 which we are here confronted. 



Let us imagine ourselves, on a cold and clear winter night, sud- 

 denly transferred from this greatest and noisiest of American 

 cities, hundreds of miles away, into the stillness of the country, or 

 into the depth of some solitary forest. 



Nothing around us seems to stir ; we are far from the roar of 

 cities ; above us the silence of the stars, beneath us a soft carpet 



