58o 



NATURE 



[April 21, 1 88 1 



of papers published in the decades of the Geological 

 Survey of the United Kingdom are among the most 

 valuable of the works issued by that body. An ex- 

 cellent man of business, Sir Philip took an active part 

 in the administration of the British Museum, the London 

 University, the Geological Society, and other institutions 

 for the promotion of science. All who knew him will miss 

 the kindly face and cheerful manners which distinguished 

 him. Only two days before his death he was in his place 

 in Parliament, but a chill caught during the lately preva- 

 lent east winds proved rapidly fatal. At the last meeting 

 of the Geological Society the vice-president, Mr. J. 

 Whitaker Hulke, F.R.S., made announcement of his 

 death, and the suldenand une.xpected tidings concerning 

 one who was so widely known and so universally 

 respected cast a sad gloom over the proceedings of the 

 evening. 



A correspondent sends us the following additional note 

 on the late Sir Philip Egerton : — 



The knowledge of the e.xtinct species of fishes is one of 

 the latest additions to paleontology, and the creator of 

 this department of the science, Louis Agassiz, found the 

 richest materials for his great work in the British Isles. 

 In their acquisition he was greatly aided by Lord Cole, 

 now Earl of Enniskilien, and by Sir Philip de Malpas 

 Grey Egerton, Bart., M.P. Their gatherings resulted in 

 most complete collections of fossil fishes, and science is 

 much indebted to the catalogues drawn up and published 

 by Sir P. Egerton of that preserved at Oulton Park. 

 Besides the species named by Agassiz this collection 

 includes many which have been subsequently determined 

 and described by Sir P. Egerton, whose name will be 

 ever associated with that of Agassiz in palichthyology. 

 In his public career Sir Philip Egerton has been distin- 

 guished by his unremitting attention to his parliamentary 

 duties in the long period since his election in 1830. The 

 British Museum sustains a severe loss in a Trustee, 

 elected in 1851, whose scientific knowledge, sound judg- 

 ment, and administrative ability were of the greatest 

 value, especially to the Natural History Departments. 

 Sir Philip's last attendance at the Board was but a few 

 days — apparently in his usual good health — before his 

 lamented death. 



THE SCIENTIFIC PRINCIPLES INVOLVED IN 

 ELECTRIC LIGHTING 



FOUR Cantor Lectures on this interesting subject have 

 just been delivered at the Society of Arts by Prof. 

 W. Grylls Adams, F.R.S. ; the lectures will be published 

 in full in the Journal of the Society of Arts, but we are 

 able to give an abstract of them by Prof. Adams. In the 

 first lecture, the discoveries of CErsted, Ampere, Arago, 

 and the early discoveries of Faraday on magnetic and 

 current induction were considered in their relation to the 

 principles of conservation and transformation of energy. 



Lecture I. — Prof. Adams began by stating and illustrating 

 the fact that important discoveries, after they are made, 

 often pass through a stage of neglect or a stage of quiet 

 development, then enter on the practical stage, when new 

 facts and new inventions follow with great rapidity. 

 The potential energy of the discoverer is transformed 

 into energy of action in many directions with more or 

 less efficiency, according to the retarding state of the 

 medium through which tbat action takes place. 



Electrical science has passed through these stages, 

 whether we regard telegraphy from the work of Sir 

 Francis Ronalds in 1816, who said, " Let us have 

 electrical conversazione offices communicating with each 

 other all over the kingdom," down to the establishment of 

 telephonic exchanges, or whether we consider electric 

 lighting from the grand experiment of Sir Humphry 

 Davy in 181 3 with a battery of 2000 cells, down to the 



latest results obtained by means of the most recent 

 magneto- or dynamo-electric machines. 



In the year 181 9 CErsted observed the action of a 

 current of electricity on a suspended magnetic needle, 

 and in the year 1820 Ampere studied the laws of their 

 mutual actions, and propounded his celebrated theory of 

 magnets and of terrestrial magnetism, making magnetism 

 the resultant action of electric currents. In the Fame 

 year Arago discovered the magnetisation produced by 

 electric currents, laying the foundation of the subject of 

 electro-magnetism. 



The discoveries of CErsted, Amp&re, and Arago were 

 fully illustrated by experiments, and their connection 

 with one another explained. In the same year, 1820, 

 Schweigger invented the galvanometer, and in 1827 Ohm 

 deduced his simple theory of the action of batteries from 

 the principle of Volta. 



The relation of the experiments of CErsted, Ampere, 

 and Arago to the principle of conservation of energy was 

 then fully considered. Considering Ampil're's e.xperi- 

 ment of the motion of wires towards one another 

 when like parallel currents are flowing in them, it was 

 shown that the currents must be diminished whilst they 

 are actually approaching, and increased whilst they are 

 separating, and so by supposing one of the original cur- 

 rents very small, the relation between Ampere's results 

 and the induction of a current by moving a wire in the 

 neighbourhood of another current was deduced. 



The laws of induced currents were then explained and 

 illustrated by some of the early experiments of Faraday, 

 who discovered the induction of electric currents by 

 magnets in 1831. 



" In his first series of papers to the Royal Society 

 entitled — (i) On the Induction of Electric Currents, (2) 

 On the Evolution of Electricity from Magnetism, (3) On 

 a New Electrical Condition of Matter, (4) On Arago's 

 Magnetic Phenomena, Faraday unfolds step by step the 

 laws of the induced current in a helix of wire B, placed 

 near to another helix A, carrying a voltaic current. 



"That as long as a steady current was maintained in 

 A there was no current induced in B ; that on making 

 contact in A or on approaching the wires there was a 

 momentary inverse current in B, and on breaking contact 

 in A or on separating the wires, there was a direct 

 induced current in B. That as this current was of the 

 nature of an electric wave like the shock of a Leyden jar, 

 it might magnetise a steel needle, although it produced 

 slight effect on a galvanometer, and how this expectation 

 was confirmed, and that the needle was magnetised 

 opposite ways on making and on breaking contact." 

 Then in his evolution of electricity from magnetism he 

 gives an account of the greatly increased eft'ects on intro- 

 ducing soft iron cores into his helices of wire, and 

 shows that similar effects are obtained by using ordi- 

 nary magnets in place of a helix carrying a battery 

 current round an iron core, i.e., in place of an electro- 

 magnet. He then describes the experiment of introducing 

 a magnet into a coil of wire, and shows that the same 

 current is obtained whether the marked end of the mag- 

 net be introduced at one end of the coil or the unmarked 

 end introduced at the other, and that a current is pro- 

 duced in the opposite direction to the former on with- 

 drawing the magnet from either end. Then after describ- 

 ing the method of producing his induction spark and also 

 muscidar contractions of a frog by means of a loadstone 

 and coil, and remarking that the intensity of the effect 

 produced depends upon the rate of separation of the coil 

 from the poles of the loadstone, he concludes this section 

 thus : An agent which is conducted along metallic wires 

 in the manner described ; which, whilst so passing, 

 possesses the peculiar magnetic action and force of a 

 current of electricity ; which can agitate and convulse 

 the limbs of a frog, and which finally can produce a 

 spark, can only be electricity. 



