94 TRANSACTIONS OF THE CANADIAN INSTITUTE. [YOL. II. 



That something, whose existence is thus proved, we call ether, and 

 since its function was at first supposed to be the transmission of light it 

 was called the luminiferous ether. 



Now, however, it is supposed and indeed may be considered as proved 

 that this wonderful ether (whose name is derived from its connection 

 with the now generally accepted undulatory theory of light) performs 

 functions of a much more varied and important nature. The recent 

 investigations of natural philosophers show that it also acts as a medium 

 for conveying not only light but also radiant heat, magnetic disturbances 

 and other forms of energy. Indeed the term luminiferous is so mis- 

 leading and inadequate that in a paper read before this Institute seven 

 years ago I rather presumptuously ventured to suggest that the term 

 ' energipherous ' would be more appropriate. Not only does the ether 

 act as a medium for the conveyance of heat, light, &c., but it also plays 

 a very important part in transforming one kind or rather form of energy 

 into various other forms. The well established fact that light is capable 

 of producing various chemical changes shows that the vibrations of the 

 ether particles in which consists light may be transformed into the 

 motions of the atoms of bodies, since all chemical changes result from 

 accelerations of these motions. 



The fact that heat is developed in certain chemical transformations 

 indicates the relation of the forces of chemical af^nity to heat. The 

 relation of heat to light may be seen by considering the nature of 

 radiant heat but is best shown by considering certain experiments of 

 Leslie, which prove that bodies are heated by absorbing light. In 

 performing one of the experiments devised by him for the purpose of 

 ascertaining the mechanical equivalent of heat. Joule discovered that 

 current electricity was a form of energy and subject to the law of 

 conservation. His results were extended by Helmholtz, Meyer, 

 Clausius and Thomson, till the law of conservation has been shown to 

 govern all natural forces. Thomson demonstrated that Faraday's dis- 

 covery of the rotation of the plane of polarization of a polarized ray of 

 light produced by media under the influence of a powerful magnet, 

 involved the dependence of magnetism on motion in the case of both 

 magnetic and diamagnetic bodies. 



To Helmholtz and Carpenter is principally due the credit of having 

 extended the principles of the conserv^ation and transformation of energy 

 to physiological phenomena. 



From data supplied by Weber, Maxwell found that electro magnetic 

 disturbances were propagated with the same velocity as light. The 



