Foundations of the Universe 261 



ing the quite invisible particles of dust in the tube; and the 

 method was now successfully applied to the new rays. Yet 

 another method was to direct a slender stream of the particles 

 upon a chemical screen. The screen glowed under the cannon- 

 ade of particles, and a powerful lens resolved the glow into 

 distinct sparks, which could be counted. 



In short, a series of the most remarkable and beautiful ex- 

 periments, checked in all the great laboratories of the world, set- 

 tled the nature of these so-called rays. They were streams of 

 particles more than a thousand times smaller than the smallest 

 known atom. The mass of each particle is, according to the latest 

 and finest measurements T imr of that of an atom of hydrogen. 

 The physicist has not been able to find any character except 

 electricity in them, and the name "electrons" has been generally 

 adopted. 



The Key to many Mysteries 



The Electron is an atom, of disembodied electricity; it oc- 

 cupies an exceedingly small volume, and its "mass" is entirely 

 electrical. These electrons are the key to half the mysteries of 

 matter. Electrons in rapid motion, as we shall see, explain what 

 we mean by an "electric current," not so long ago regarded as 

 one of the most mysterious manifestations in nature. 



"What a wonder, then, have we here!" says Professor R. K. 

 Duncan. "An innocent-looking little pinch of salt and yet pos- 

 sessed of special properties utterly beyond even the fanciful 

 imaginings of men of past time; for nowhere do we find in the 

 records of thought even the hint of the possibility of things which 

 we now regard as established fact. This pinch of salt projects 

 from its surface bodies [i.e. electrons] possessing the inconceiv- 

 able velocity of over 100,000 miles a second, a velocity sufficient 

 to carry them, if unimpeded, five times around the earth in a 

 second, and possessing with this velocity, masses a thousand times 

 smaller than the smallest atom known to science. Furthermore, 



