TRANSACTIONS OF SECTION A. 615 



first of chemical and then of magnetic and electric phenomena. In the words of 

 the historian Hallam, writing in 1839, ' in his Latin treatise on the Magnet he 

 not only collected all the knowledge which others had possessed, but he became 

 at once the father of experimental philosophy in this island ; ' and no demur 

 would be raised if Hallam's restriction to this country were removed. Worlsiog 

 nearly a century bi-l'ore the time when the astronomical discoveries of Newton had 

 originated the idea of attraction at a distance, he established a complete formu- 

 lation of the interaction of magnets by what we now call the exploration of their 

 fields of force. His analysis of the facts of magnetic influence, and incidentally of 

 the points in which it diflers from electric influence, is virtually the one which 

 Faraday re-introduced. A cardinal advance was achieved, at a time when the 

 Copernican Astronomy had still largely to make its way, by assigning the 

 behaviour of the compass and the dip needle to the fact that the earth itself is a 

 great magnet, by whose field of influence they are controlled. His book passed 

 through many editions on the Continent within forty years : it won the high 

 praise of Galileo. Gilbert has been called ' the father of modern electricity by 

 Priestley, and ' the Galileo of magnetism ' by Poggendortf. 



When the British Association last met at Bradford in 1873 the modern theory 

 which largely reverts to Gilbert's way of formulation, and refers electric and 

 magnetic phenomena to the activity of the aether instead of attractions at a 

 distance, was of recent growth: it had received its classical exposition only two 

 years before by the publication of Clerk Maxwell's treatise. The new doctrine 

 was already widely received in England on its own independent merits. On the 

 Continent it was engaging the strenuous attention of Helmholtz, whose series of 

 memoirs, deeply probing the new ideas in their relation to the prevalent and 

 fairly successlul theories of direct action across space, had begun to appear in 

 1870. Daring many years the search for crucial experiments that would go 

 beyond the results equally explained by both views met with small success ; it 

 was not until 1887 that Hertz, by the discovery of the aethereal radiation of long 

 wave-length emitted from electric oscillators, verified the hypothesis of Faraday 

 and Maxwell and initiated a new era in the practical development of phy>ical 

 science. The experimental field thus opened up was soon fully occupied both in 

 this country and abroad ; and the borderland between the sciences of optics and 

 electricity is now being rapidly explored. The extension of experimental know- 

 ledge was simultaneous with increased attention to directness of explanation ; the 

 expositions of Heaviside and Hertz and other writers fixed attention, in a manner 

 already briefly exemplifled by Maxwell himself, on the inherent simplicity of the 

 completed aet'hereal scheme, when once the theoretical scaftbldiug employed in its 

 construction and dynamical consolidation is removed ; while Poyncing's beautiful 

 corollary specifying the path of the transmission of energy through the sether 

 has brought the theory into simple relations with the applications of electro- 

 dynamics. 



■Equally striking has been the great mastery obtained during the last twenty 

 years over the practical manipulation of electric power. The installation of 

 electric wires as the nerves connecting difl'erent regions of the earth had attained 

 the rank of accomplished fact so long ago as 1857, when the first Atlantic cable 

 was laid. It was largely the theoretical and practical difficulties, many of them 

 unforeseen, encountered in carrying that great undertaking to a successful issue, 

 that necessitated the elaboration by Lord Kelvin and his coadjutors of convenient 

 methods and instruments for the exact measurement of electric quantities, and 

 thus prepared the foundation for the more recent practical developments in 

 other directions. On the other hand, the methods of theoretical explanation have 

 been in turn improved and simplified through the new ways of considering the 

 phenomena which have been evolved in the course of practical advances on a 

 large scale, such as the improvement of dynamo armatures, the conception and 

 utilisation of magnetic circuits, and the transmission of power by alternating 

 currents. In our time the relations of civilised life have been already perhaps 

 more profoundly altered than ever before, owing to the establishment of practically 

 instantaneous electric communication between all parts of the world. The 



