Sept. 7, 1876] 



NATURE 



387 



a given amount of energy of one form into energy of 

 another form, and then, reversing the process, reconvert 

 the energy of the second form thus obtained into the 

 ori^itial qitantily of energy of the first form. In fact, 

 during any transformation of energy from one form into 

 another, there is always a certain portion of the energy 

 changed into heat in the process of conversion ; and the 

 heat thus produced becomes dissipated and diffused by 

 radiation and conduction. 



Consequently there is a tendency in nature for all the 

 energy in the universe, of whatever kind it be, gradually 

 to assume the form of heat, and, having done so, to be- 

 come equally diffused. Now, were all the energy of the 

 universe converted into uniformly diffused heat, it would 

 cease to be available for producing mechanical effect, 

 since for that purpose we must have a hot source and a 

 cooler condenser. This gradual degradation of energy is 

 perpetually going on ; and sooner or later, unless there 

 be some restorative power, of which we at present have 

 no knowledge whatever, the present state of things must 

 come to an end. 



We must pass very briefly over a large number of Sir 

 W. Thomson's contributions to science that, were our 

 limits less circumscribed, we would gladly dwell upon. 

 In 1855 his paper on " Electrodynamics of Qualities of 

 Metals" was made the Bakerian Lecture for the year. 

 This paper represents a marvellous amount of ingenuity 

 and labour and contains, most valuable new results that, 

 strange to say, are only now beginning to be known. In 

 it was announced his discovery of the electric convection 

 of heat, and a great number of most important new rela- 

 tions between thermal and electric properties of matter. 

 It is interesting to remark that it was while engaged in 

 these investigations that Thomson first called in the ex- 

 perimental aid of his students, and thus made a beginning 

 of the Glasgow Physical Laboratory. 



We can do no more than mention here Sir William 

 Thomson's proof of electricity of contact, his calculation 

 of the size of atoms, his memoir on the mechanical ener- 

 gies of the solar system, his determination of the rigidity 

 of the earth, his researches on the tides in connection 

 with a British Association Committee on that subject, 

 and his recent splendid researches on vortex motion, as 

 we have still to refer to his connection with submarine 

 telegraphy. 



In 1854 Faraday, with an experimental cable, investi- 

 gated the cause of the retardation 0/ signals first ohservtdi 

 in the working of the cable between Harwich and the 

 Hague. Thomson, taking up the question published 

 an investigation of the nature of the phenomenon, one 

 practical result of which was that with cables similar in 

 lateral dimensions the retardations are proportional to 

 the squares of the lengths. This law is now commonly 

 referred to as the " law of squares." About this time it 

 was proposed to construct a cable to connect England 

 with America ; and it became obvious that the discovery 

 of the retardation of signals raised a question whether 

 the transatlantic cable would not prove a commercial 

 failure. Whitehouse, experimenting with 1,125 miles of 

 cable, found the transmission of an instantaneous signal 

 to the farther end of the cable to occupy one second and a 

 half. The length of a cable required to connect Ireland 

 with Newfoundland is twice that of the experimental 



cable of Whitehouse ; and thus, according to the law of 

 squares, the time taken to transmit an instantaneous 

 signal through a cable similar in lateral dimensions to 

 that of Whitehouse, and joining those two places, would 

 be no less than six seconds. In 1856 Whitehouse read a 

 paper before the British Association, in which he de- 

 scribed experiments by which he hoped to disprove the 

 law of squares. Thomson replied in the Atherimim 

 (Nov. I, 1856) ; and subsequent experiments have esta- 

 blished the correctness of his law. 



Fortunately a true understanding of the nature of the 

 phenomenon of retardation led Prof. Thomson to the 

 method of overcoming the difficulties presented. The 

 disturbance produced at the extremity of a long sub- 

 marine cable by the application for an instant of 

 electromotive force at the other end is not, as in the case 

 of a signal through an overhead land-line, a pulse, prac- 

 tically infinitely short, and received only a minute frac- 

 tion of a second after it was communicated. Instead of 

 this, a long wave is observed at the farther extremity, 

 gradually swelling in intensity, and as gradually dying 

 away. Its duration for such a cable as we have been 

 speaking of would be the whole six seconds, calculated 

 from the experiments of Whitehouse. Prof. Thomson 

 perceived that an instrument was required which should 

 give an indication of a signal received long before the 

 wave has acquired its maximum intensity, and in which 

 the subsequent rising to maximum intensity should not 

 render unreadable a fresh signal sent quickly after the 

 previous one. This was effected by his " mirror galvano- 

 meter " ; and it was by means of it that the messages 

 transmitted through the 1858 Atlantic cable were read. 



The 1858 cable, submerged under difficulties that many 

 times threatened to be insurmountable, soon failed. 

 Several important messages were, however, transmitted 

 through it ; and it served to prove the feasibility of the 

 project which many eminent engineers up till that time 

 regarded as chimerical. Before another attempt was 

 made the labours of Prof. Thomson and others, to all of 

 whom the world owes a deep debt of gratitude, had so 

 improved the construction of the cables and the mecha- 

 nical arrangements for submersion, that though many 

 difficulties presented themselves they were all, in 1866, 

 triumphantly overcome. It was on his return from the 

 submersion of the 1866 cable, and the raising and the 

 completion of the 1865 cable, that the honour of knight- 

 hood was conferred on him along with others of his dis- 

 tinguished fellow-workers. 



Recently Sir William Thomson has invented a new 

 and very beautiful instrument, the " siphon recorder," 

 for recording signals on long submarine lines. It is in 

 use at all the telegraph stations along the submarine line 

 connecting England with India. It is also used on the 

 French Atlantic Cable, and on the direct United States 

 line. Sir W. Thomson, Mr. Varley, and Prof. Jenkin, 

 combining their inventions together, have given the only 

 system by which submarine telegraphy on long lines has 

 been carried on up to the present time. 



Sir William Thomson is an enthusiastic yachtsman 

 and a skilful navigator. His recently-published popular 

 lecture on Navigation proves this ; and, with that bright 

 genius which enriches all with which it comes in contact, 

 his improvements in navigation, as we had occasion to 



