440 THE POPULAR SCIENCE MONTHLY 



time and of careful work. We are at present engaged not only in 

 checking tliis value under new sets of conditions, but in redetermining 

 all of the quantities which enter into it. Assuming it as the basis of 

 our computation there are in a cubic centimeter of gas under normal 

 conditions 2.70 X 10^^ molecules and the weight of a hydrogen atom 

 is 1.735 X 10"-* grams. These numbers can be made more significant 

 to the ordinary reader with the aid of an illustration. If a million men 

 were to be set counting as fast as they could count, say at the rate of 

 200 a minute, they could count out the number of molecules in a cubic 

 centimeter in just 252 thousand years if none of them ever stopped to 

 eat, sleep, or die. 



" But,'' says some one, " What of it any way ? Does the triumph 

 or defeat of the kinetic theory of matter or the atomic theory of elec- 

 tricity have anything to do with the practical problems of the modern 

 world ? Is anybody going to be better fed or better clothed because of 

 it ? " the answer is, " Within the past seventy-five years — the merest 

 drop in the bucket of recorded time — the conditions of human life on 

 this earth have been completely revolutionized, and that solely because, 

 for the first time in history, man has become interested in considerable 

 numbers, rather than, as heretofore in isolated instances, in patiently 

 and persistently seeking merely to uncover nature's ' useless ' secrets, 

 and then, when the inner workings have been laid bare, has in many 

 cases seen a way to put his brain inside the machine and drive it where 

 he would. Every increase then in man's knowledge of the way in which 

 nature works must in the long run increase by just so much man's abil- 

 ity to control nature and to turn her hidden forces to his own account." 



