676 THE POPULAR SCIENCE MONTHLY. 



ing moment. One feels that the destiny of man is assuredly 

 noble. 



The student will not go far in his quest before facts begin to 

 accumulate which are fraught with the deepest significance. He 

 has known perfectly well all along that only a certain amount of 

 heat can be obtained from burning a definite quantity of coal, and 

 that it will be given out in proportion to the rapidity with which 

 the burning is accomplished. If he wishes his room to be warmer, 

 he opens the draught and gives a more abundant supply of air to 

 the fire. The operation has been too often repeated to excite any 

 wonder. But it becomes significant when he discovers that all 

 other chemical reactions rest upon precisely the same principle. 

 Each substance is found to have a definite combining power, and 

 in every reaction, however simple or complex it may be, a definite 

 quantity of one element unites with a definite quantity of another. 

 If too much of either element be taken, it will be left over. But 

 this is the law of definite proportions discovered by Dr. Dalton in 

 the early part of the century and now the very corner-stone of 

 chemical science. If the student further inquire what has become 

 of the coal and the oxygen whose union we call combustion, he 

 will find that a colorless gas, carbonic-acid gas, has been formed 

 whose weight is exactly equal to the sum of their weights. Other 

 illustrations will yield parallel results, and the far-reaching con- 

 clusion will be forced upon him that man is neither able to create 

 matter nor to destroy it. This single truth once really appre- 

 hended gives a stability to thought which can scarcely come from 

 any other single consideration. The universe is seen to be in an 

 eternal ebb and flow, but its materials are seen to be constant. 

 Once persuaded of the fact, and the suspicion arises that the same 

 may be the case with heat and other forms of motion. And such 

 he finds to be the truth. He learns that energy likewise is neither 

 creatable nor destructible, and that all the work going on in the 

 universe is simply that of transformation. New distributions of 

 motion and new combinations in matter, these make up the cosmic 

 life, but the sum total in each case remains unaltered. Perpetual 

 motion is seen to be more than a possibility ; it is found to be a 

 necessity. One sees all of the universe in a state of ceaseless flux, 

 sees that nothing stands still, that growth involves never-ending 

 change, and becomes prepared to accept without fear those 

 changes of opinion which intellectual growth necessitates as well 

 as that great change of state which we call death. I can not hold 

 as idle or of secondary import the speculations which these con- 

 siderations engender. It is good for a man to penetrate as far as 

 he may into the established order of the universe, for its secret is 

 his secret, its process is his process. Curious thoughts spring 

 from brooding over these doctrines of the conservation of force 



