46 The Outline of Science 



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The Bricks of the Cosmos 



More than two thousand years ago the first men of science, 

 the Greeks of the cities of Asia Minor, speculated on the nature 

 of matter. You can grind a piece of stone into dust. You can 

 divide a spoonful of water into as many drops as you like. Ap- 

 parently you can go on dividing as long as you have got appara- 

 tus fine enough for the work. But there must be a limit, these 

 Greeks said, and so they supposed that all matter was ultimately 

 composed of minute particles which were indivisible. That is 

 the meaning of the Greek word "atom." 



Like so many other ideas of these brilliant early Greek 

 thinkers, the atom was a sound conception. We know to-day that 

 matter is composed of atoms. But science was then so young 

 that the way in which the Greeks applied the idea was not very 

 profound. A liquid or a gas, they said, consisted of round, 

 smooth atoms, which would not cling together. Then there were 

 atoms with rough surfaces, ''hooky" surfaces, and these stuck 

 together and formed solids. The atoms of iron or marble, for 

 instance, were so very hooky that, once they got together, a strong 

 man could not tear them apart. The Greeks thought that the 

 explanation of the universe was that an infinite number of these 

 atoms had been moving and mixing in an infinite space during an 

 infinite time, and had at last hit by chance on the particular com- 

 bination which is our universe. 



This was too simple and superficial. The idea of atoms was 

 cast aside, only to be advanced again in various ways. It was the 

 famous Manchester chemist, John Dalton, who restored it in the 

 early years of the nineteenth century. He first definitely formu- 

 lated the atomic theory as a scientific hypothesis. The whole 

 physical and chemical science of that century was now based upon 

 the atom, and it is quite a mistake to suppose that recent discover- 

 ies have discredited "atomism." An atom is the smallest particle 



