WHAT THIS WORLD IS MADE OF 



primal senses. There is probably not a great deal 

 of native difference in the mental capacity of a fine 

 type of a savage and that of a Spencer or a Des- 

 cartes. 



Clerk-Maxwell, the great physicist of Cambridge, 

 was wont to say that progress was symbolized in 

 the clock, the balance, and the foot-rule. It is 

 because we know accurately how to weigh, to 

 measure, and to time that we know more than the 

 ancients, and the fact that some few of their 

 random guesses have turned out to be true speaks 

 rather for the simplicity of nature than for their 

 intelligence. It is because this later day has con- 

 trived subtle ways of counting and measuring that 

 we have come to know something of the way our 

 familiar world is constructed. 



It seems to be made up of very small particles, 

 perfectly definite in size and weight, and, curiously 

 enough, not varying greatly in their dimensions 

 one kind from another. These ultimate particles, 

 or molecules, as the physicist calls them, may be 

 measured in a variety of ways, and as the result of 

 these measurements it seems probable that New- 

 ton with his soap-bubble rings, Faraday with his 

 gold-plates, Professor Rontgen with his thin layers 

 of oil, have approached very closely the actual 

 dimensions of a molecule; in other words, that 

 present-day science has reached the borders of 



"5 



