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CHAPTER III 



" rs 5 



SOME X-RAY MIRACLES 



Sir William Bragg and his 'Jolly ' Occupations 



NOT so many years ago the atom was looked upon 

 as a hard little particle, the brick with which 

 matter was built up. Then came doubts on the 

 subject, and more doubts, until the solid atom as thought 

 of in Victorian times was proved by Rutherford and 

 others to be a number of tiny specks floating or revolving 

 in void. Professor Eddington says that Einstein and 

 Rutherford are the ' villains of the piece/ but what 

 about Bragg, who proved that one atom could go right 

 through another? 



The atom, as we now know it, resembles a planetary 

 system with satellites revolving around a central sun. 

 Now the planets of our own system are so far apart — the 

 new planet is no less than four thousand million miles 

 away from the sun — that it is quite possible to imagine a 

 second planetary system passing through ours without 

 any collision occurring between the various members of 

 the two systems. And that, in fact, seems to be exactly 

 what happens when two atoms meet. Unless there is a 

 collision between the protons, the inconceivably small 

 centres of the atoms — and the chance is about a million 

 to one against it — the two atoms pass through one 

 another without damage to their constituent parts. 



That has been proved — definitely proved — in a famous 

 experiment carried out by Sir William Bragg, who made 

 an atom of helium take a perfectly straight path through 

 an inch of air. An inch does not seem much, yet it is 

 a huge journey when considered in terms of atoms, a 



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