388 Structure of the Universe 



ing in space, it would seem to our better judgment that there must 

 be some sort of mechansm which transmits this gigantic force. Other 

 considerations lead us to this conclusion. We know that powerful 

 magnetic storms originating in the sun are transmitted instantan- 

 eously to the earth and throughout the whole solar system with such 

 intensity occasionally as to put many of the telegraph instruments 

 and wires in the country out of commission until they pass. 



The Density of the Medium. 



Until recent years very little of a definite nature has been known 

 as to the nature of the medium of space. So far as any evidence it 

 gives of its existence to our senses is concerned, it would appear to 

 be something very unsubstantial, and for this reason it has been called 

 the "ether." Newton had an idea that it was a very thin, highly 

 attenuated fluid which pervaded all space, so very thin in fact, that if 

 you could scatter a pill box full of air throughout the space of the 

 solar system its density would then be about the density of the ether 

 oi space. 



With the development of electrical science and the study of electric 

 and magnetic forces, however, different ideas began to be entertained 

 as to the density of the so-called ether, until to-day we have the 

 leading physicists postulating the necessity for an ether of very 

 high density and very much greater than the density of any known 

 substance. In his Yale lectures on "Electricity and Matter" Sir J. J. 

 Thomson, in discussing the nature of electrical mass, says: "The view 

 I wish to put before you is that it is not merely a part of the mass 

 of a body which arises in this way, but that the whole mass of any 

 body is just the mass of ether surrounding the body which is carried 

 along by the Faraday tubes associated with the atoms of the body. 

 In fact, that all mass is mass of the ether, all momentum, momentum 

 of the ether, and all kinetic energy kinetic energy of the ether. This 

 view, it should be said, requires the density of the ether to be im- 

 mensely greater than that of any known substance." And in his 

 presidential address to the British Association at Winnipeg last 

 August he said: "Since we know the volume of the corpuscle as well 

 as the mass, we can calculate the density of the ether attached to the 

 corpuscle; doing so, we find it amounts to the prodigious value of 

 about 2,000 million times that of lead." He states, however, that this 

 density would be the density of the ether only in the immediate vicin- 

 ity of the corpuscle, and that its density in free space would not be 

 so high if the ether is not compressible. Sir Oliver Lodge, in his last 

 edition of "Modern Views of Electricity" also says: "The ether is now 

 turning out to be by far the most substantial body known, — in com- 

 parison with which the hitherto contemplated material universe is like 

 a vapor of extreme tenuity, — a barely perceptible filmy veil." 



These conclusions of Thomson and Lodge as to the density of the 

 medium of cpace are arrived at by the study of electromagnetic and 

 •electrostatic forces. Professor Reynolds works out his conclusions 

 from mechanical and dynamical considerations, and arrives at the 

 density of the medium ol space as being ten thousand times that of 



