igo THE POPULAR SCIENCE MONTHLY. 



live, it experiences the same number of things as we do from the 

 cradle to the grave. Its measure of time, compared with ours, 

 would be infinitely smaller. 



Such a being could live on an atom just as conveniently as we 

 live on this planet of ours. If, for instance, the quickness of its 

 sensations were to ours as one thousand trillions is to one, it would 

 experience in the time of one light- vibration — that is, in one five 

 hundred billionth of a second — as much as we in eight months. 

 The atom on which it lived would be its world ; the molecule to 

 which the latter belonged, its solar system ; and by the revolution 

 of atoms it could count its days and years. Above him, our atom- 

 citizen would see other similar and far-distant worlds ; for, the 

 molecules, perhaps all belonging to one tiny air-bubble, would 

 form the star-cluster of his firmament. 



A magnification of ten thousand trillion diameters would en- 

 large the little air-bubble to the dimensions of our entire stellar 

 system, the star-cluster of which the limits are the outermost re- 

 gions of the milky way. But, great as the host of our stars may 

 appear to us, the firmament of our atom-inhabitant would be still 

 more densely crowded ; for while we, with the aid of our best tele- 

 scopes, can not see more than about twenty million stars, the little 

 air-bubble would harbor at least fifty thousand billions. 



Now, you might object that, to an atom-inhabitant, the mole- 

 cules of a gas could not possibly appear as the fixed stars do to us, 

 inasmuch as these molecules experience, on an average, about 

 eighty million collisions in every second. However, it must not 

 be forgotten that we have reduced the time of life and observa- 

 tion of our atom-inhabitant to one thousand trillionth that of our 

 own. During this brief moment the relative positions of the 

 visible molecules — to him far-distant suns — will appear just as 

 unaltered, and their courses or orbits to the atom-astronomers 

 just as linear, as those of our fixed stars appear to us. 



What is the short space of time, the trifling moment, that we 

 know of the life-history of the earth, compared with the eternities 

 which must elapse before two fixed stars approach sufficiently 

 close to render a collision inevitable ? Our records of human his- 

 tory read back only a few thousand years, and of the age of our 

 planet we only know that it must be measured by thousands of 

 centuries. Of the courses of the fixed stars we know absolutely 

 nothing ; we only infer from certain data that their average ve- 

 locity is about a hundred times greater than that of our molecules. 



Thus the atom-inhabitants are about as wise as we are. The 

 life of the entire human race, so far as our historical records are 

 concerned, would, if condensed to one thousand trillionth, occupy 

 about the one thousand millionth part of a second — less than one 

 twentieth of the time which elapses, on an average, before the col- 



