MIRACLES OF SCIENCE 



which are interpreted as heat or light or electro 

 magnetism, and which are rushing through space at 

 the speed of 186,000 miles per second, wash against 

 any object that lies in their path with an actual pres- 

 sure manifesting themselves as a positive push, in 

 addition to their other effects. 



This is quite what one might expect, perhaps, were 

 it not that the ether is so exceedingly intangible an 

 entity one dare not say substance. Clerk-Maxwell, 

 the most famous student of the ether, did indeed 

 declare, from theoretical considerations, that this 

 push must take place. But between theory and 

 demonstration there may be a wide gap, and it re- 

 mained for the experiments of Professor Lebedew 

 in Europe and of Professors Nichols and Hull in 

 America, undertaken simultaneously but quite in- 

 dependently, to place the matter beyond dispute. 

 Now we know that every ray of sunlight gives a posi- 

 tive push to any material substance it reaches, and 

 that a similar push accompanies all other radiations. 



And as every body not at the absolute zero of 

 temperature a degree of cold never yet attained 

 in a terrestrial laboratory, and obtaining, if any- 

 where, only in the depths of interstellar space is 

 giving off radiations, it follows that all bodies are 

 pushing and tending to repel all other bodies that 

 their radiations can reach. 



The instrument that has demonstrated the exist- 

 ence of this hitherto only vaguely suspected force 

 consists of two discs of thin glass (one disc blacken- 

 ed, the other polished), suspended by a quartz thread 

 in a vacuum. When waves of radiant energy impinge 



no 



