Sept. 20, 1888] 



NA TURE 



499 



along the bank of the Thames at Woolwich. The fuse was ex- 

 ploded during a heavy thunderstorm. The knowledge of the 

 causes of a danger is a sure means for the production of its 

 removal, or of its reduction to a minimum. Low-tension fuses 

 and metallic circuits reduce the evils of lightning, but have not 

 removed them. Should war unhappily break out again in 

 Enrrpe, submarine mining will play a very serious part ; and, 

 paradoxical as it may appear— as has been suggested by the 

 French Ambassador, M. Waddington — its very destructiveness 

 may ultimately prove it to be a powerful element of peace. 



It seems incredible that, having utilized this great power of 

 Nature to such a wide and general extent, we should be still in a 

 state of mental fog as to the answer to be given to the simple 

 question — What is Electricity ? The engineer and the physicist 

 are completely at variance on thi^ point. The engineer regards 

 electricity, like heat, light, and sound, as a definite form of 

 •energy, something that he can generate and destroy, something 

 that he can play with and utilize, something that he can measure 

 and apply. The physicist — at least some physicists, for it is 

 difficult to find any two physicists that completely agree with 

 each other — regard electricity as a peculiar form of matter per- 

 meating all space as well as all substances, together with the 

 luminiferous ether, which it permeates like a jelly or a sponge. 

 Conductors, according to this theory, are holes or pipes in this 

 jelly, and electrical generators are pumps that transfer this 

 hypothetical matter from one place to another. Other physicists, 

 following Edlund, regard the ether and electricity as identical ; 

 and some, the disciples of Helmholtz, consider it as an integral 

 constituent of Nature, each molecule of matter having its own 

 definite charge, which determines its attraction and its repulsion. 

 All attempts to revive the Franklinian, or material, theory of 

 electricity, have, however, to be so loaded with assumptions, and 

 so weighted with contradictions, that they completely fail to 

 Temove electricity from the region of the mysterious. It. is 

 already extremely difficult to conceive the existence of the ether 

 itself as an infinitely thin, highly elastic medium, filling all space, 

 employed only as the vehicle of those undulat' ry motions that 

 give us light and radiant heat. The material theory of electricity 

 requires us to add to this another incomprehensible medium 

 •embedded or entangled in this ether, which is not only a medium 

 for motion, but which is itself moved. The practical man, with 

 his eye and his mind trained by the stem realities of daily ex- 

 perience, on a scale vast compared with that of the little world 

 ■of the laboratory, revolts from such wild hypotheses, such 

 unnecessary and inconceivable conceptions, such a travesty of 

 the beautiful simplicity of Nature. 



He has a clear conception of electricity as something which 

 has a distinct objective existence, which he can manufacture and 

 sell, and something which the unphilosophic and ordinary mem- 

 ber of society can buy and use. The physicist asserts dog- 

 matically : " Electricity may possibly be a form of matter — it is 

 not a form f'f energy." The engineer says distinctly: "Elec- 

 tricity is a form of energy — it is not a form of matter ; it obeys 

 the two great developments of the present generation — the 

 mechanical theory of heat and the doctrine of the conservation of 

 energy." There must be some cause for this strange difference 

 of views. It is clear that the physicist and the engineer do not 

 apply the term electricity to the same thing. The engineer's 

 electricity is a real form of energy ; the speculative philosopher's 

 electricity is a vague subjective unreality which is only a mere 

 factor of energy and is not energy itself. This factor, like force, 

 gravity, life, must, at any rate for the prespnt, remain unknow- 

 able. It is not known what force is ; neither do we know what 

 is nutter or gravity. The metaphysician is even doubtful as 

 regards time and space. Our knowledge of these things com- 

 mences with a definition. The human mind is so unimpression- 

 able, or language is so poor, that writers often cannot agree even 

 on a definition. The definition of energy is capacity for doing 

 work. We practical men are quite content to start from this 

 fiducial line, and to affirm that our electricity is a something 

 •which has a capacity for doing work ; it is a peculiar form of 

 energy. The physicist may speculate as much as he pleases on 

 the other side of this line. He may take the factors of energy, 

 aud mentally play with them to his heart's content ; but he must 

 not rob the engineer of his term elec ricily. It is a pity that we 

 cannot settle our difference by changing the term. Physicists 

 might leave the term e'cc'ricity to the form of energy, which is an 

 objective reality, and which the ordinary mortal understands ; 

 while engineers would be quite content if speculative physicists 

 and enthusiastic mathematicians would call their subjective un- 

 reality, their imaginary electrical matter, by some other term. If 



it be necessary to mentally create some imaginary matter to 

 fulfil the assumptions and abstractions of their mathematical 

 realizations, let them call it coulombism or electron, and not 

 appropriate the engineer's generic and comprehensive term 

 electricity. The engineer finds the motions of existing matter 

 and of the ether quite sufficient to meet all his requirements, and 

 to account for all those phenomena which are called electrical. 



It seems paradoxical to assert that two unrealities can form a 

 reality, or that two subjective ideas can become an objective one ; 

 but it must be remembered that in all electrical phenomena that 

 which makes them real and objective is derived from without. 

 The motion that renders an electrical phenomenon evident is im- 

 parted to it from some other form of energy. The doctrine of 

 the conservation of energy aserts that energy is never destroyed, 

 it is only transformed — work must be done to render it evident. 

 No single electrical effect can be adduced which is not the result 

 of work done, and is not the equivalent of energy absorbed. 

 The engineer's notion of work — something done against resist- 

 ance ; and of power — the rate at which this change of condition 

 is effected — are the key-stones to the conception of the character 

 of those great sources of power in Nature whose direction to the 

 uses and convenience of man is the immediate profession of those 

 who generally assemble together in Section G of the British 

 Association to discuss the "practical application of the most 

 important principles of natural philosophy, which has, in a con- 

 siderable degree, realized the anticipations of Bacon and changed 

 the aspect and state of affairs in the whole world." 



I cannot pretend to have given a survey of all the practical 

 applications of electricity. I have but briefly indicated the pre- 

 sent area covered by the new and rapidly-growing industry. 

 Five million people upon the globe are now dependent on the 

 electric current for their daily bread. Scarcely a week passes 

 without some fresh practical application of its principles, and we 

 seem to be only on the shore of that sea of economy and bene- 

 ficence w hich expands with every new discovery of the properties 

 of electricity, and spreads already beyond the mental grasp of 

 any one single worker. 



NOTES. 



The Geological Congress held its first meeting on Tuesday. 

 This week we print the President's address and one of the papers 

 referring to one of the most important points to be considered by 

 the Congress — that of the Crystalline Schists. 



Intelligence has been received of the murder of Major 

 Barttelot, Mr. Stanley's principal lieutenant, by some of his 

 followers when on the way from Stanley Falls with reinforcements 

 for his chief. 



The sudden death of Mr. R. A. Proctor was announced from 

 New York about a week ago. In addition to his writings on various 

 subjects for which his name is so widely known, he made some 

 contributions to the science of astronomy. Some of his books, 

 such as "Saturn and its System," his various star atlases, and 

 others we might name, have a permanent value. Elected a 

 Fellow of the Royal Astronomical Society in 1866, he was 

 for a considerable number of years the most prolific contributor 

 to the Monthly Notices. In 1871 he was elected to the Council, 

 and in the following year was appointed the Secretary. 

 The determination of the rotation-period of Mars, a chart 

 of Mars from the collation of a large number of drawings, 

 a long series of papers on transits of Venus, especially the tran- 

 sits of 1874 and 1882, and a yet more important series on the 

 distribution of stars and nebulae, were communicated to the 

 Astronomical Society during these years. It was in connection 

 with this last series that his greatest single work for science was 

 carried out, viz. the copying of the 324, 198 stars cf Argelander's 

 "Survey of the Northern Heavens, " on an "equal surface" 

 projection chart, a work that involved 400 hours of the most 

 unremitting labour. Mr. Proctor was born at Chelsea, in March 

 1834, and was educated at King's College, London, of which he 

 was Honorary Fellow, and at St. John's College, Cambridge, 

 where he won a Scholarship. He obtained his degree of B.A. 

 in i860, and his name appears as twenty-third in the Wrangler's 

 List. 



