64 Sir Oliver Lodge [Feb. 21, 



Too little is known, however, about the mechanism of gravitation 

 to enable ns to adduce it as the strongest argument in support of the 

 existence of an ether. The oldest valid and conclusive requisition of 

 an etherial medium depends on the wave theory of light, one of the 

 founders of which was your Professor of Natural Philosophy at the 

 beginning of last century, Dr. Thomas Young. 



No ordinary matter is capable of transmitting the undulations or 

 tremors that we call light. The speed at which they go, the kind 

 of undulation, and the facility with which they go through vacuum, 

 forbid this. 



So clearly and universally has it been perceived that waves must 

 be waves of something — something distinct from ordinary matter — 

 that Lord Salisbury, in his presidential address to the British Associa- 

 tion at Oxford, criticised the ether as little more than a nominative 

 case to the verb to undulate. It is truly tit at, though it is also truly 

 more than that : but to illustrate that luminif erous aspect of it, I will 

 quote a paragraph from that lecture of Clerk Maxwell's to which T 

 have already referred : — 



" The vast interplanetary and interstellar regions will no longer be 

 regarded as waste places in the universe, which the Creator has not 

 seen fit to fill with the symbols of the manifold order of His kingdom. 

 We shall find them to be already full of this wonderful medium ; so 

 full, that no human power can remove it from the smallest portion of 

 space, or produce the slightest flaw in its infinite continuity. It 

 extends unbroken from star to star ; and when a molecule of hy- 

 drogen vibrates in the dog-star, the medium receives the impulses of 

 these vibrations, and after carrying them in its immense bosom for 

 several years, delivers them, in due course, regular order, and full tale, 

 into the spectroscope of Mr. Huggins, at Tulse Hill." (It is pleasant 

 to remember that those veteran investigators Sir William and Lady 

 Huggins are still at work.) 



This will suffice to emphasise the fact that the eye is truly an 

 etherial sense-organ — the only one which we possess, the only mode 

 by which the ether is enabled to appeal to us, and that the detection 

 of tremors in this medium — the perception of the direction in which 

 they go, and some inference as to the quality of the object which 

 has emitted them — cover all that we mean by " sight " and " seeing." 



I pass then to another function, the electric and magnetic phe- 

 nomena displayed by the ether ; and on this I will only permit myself 

 a very short quotation from the writings of Faraday, whose whole life 

 may be said to have been directed towards a better understanding of 

 these ethereous phenomena. Indeed, the statue in your entrance hall 

 may be considered as the statue of the discoverer of the electric 

 and magnetic properties of the Ether of space. 



Faraday conjectured that the same medium which is concerned in 

 the propagation of hght might also be the agent in electromagnetic 

 phenomena. " For my own part," he says, " considering the relation 



