536 



NATURE 



plurimis concessum est ; uni vero plurimarum fines ex 

 tendisse raro contigit. Atqui hodie virum salutamus, qui 

 rerum naturae regioneni plusquam unam feliciter occu- 

 payit, qui prinium physiologiae penetralia perscrutatus, 

 deinde physicorum studiorum campo amplissimo potitus, 

 ipsarn denique matheniaticorum arcem fortiterexpugnavit, 

 ex alia deinceps in aliam provinciani progressus, velut 

 militum Romanotum ille maximus, ' victrices aquilas 

 alium laturus in orbem.' 



" Militarium medicorum ordini adhuc adscriptus, argu- 

 mentum magnum intra unius libelli fines artiores com- 

 plexus, ostendit vim illani, quae nonnunquam viva vocatur, 

 in universa rerum natura esse conservatam, partes eius 

 aliam ex alia posse generari, summam esse immutabilem. 

 Quid huius ingenio excogitatas commemorem quaestiones 

 illas hydrodynamicas, quid vortices illos qui scientiae 

 mathematicae ad interiora pertinent ? Ilia vero magna 

 opera, quorum in uno sensus audiendi clarissime expli- 

 catur, in altero videndi sensus pulcherrime illustratur, 

 omnes, nisi fallor, aut vidistis ipsi, aut fama certe audi- 

 vistis. Pulchrum est (uti hunc ipsum confitentem legimus), 

 pulchrum profecto est, e scopulo quodam exceho late 

 tumultuantem oceanum prospicere, tluctusque procul 

 albescentes, modo breviores, modo longiores, oculis dis- 

 cernere : pulchrius autem in physiologiae terapio intimo 

 versatum, oculorum ipsorum structuram exquisitam intro- 

 spicere, et, lucis legibus obscuris ordine lucido evolutis, 

 fluctuantes luminis motus metiri variamque colorum 

 yeriustatem explicare : omnium fortasse pulcherrimum, 

 in iisdem arcanis morantem, undas illas aeris quas nulla 

 nisi mentis aciecontemplari possumus, inter sese audiendo 

 distinguere ; sonitus cuiusque, dum tremit vibratque, in- 

 tervalla numerare ; universam denique musices theoriam 

 et mathematicis et physicis et physiologicis probavisse 

 argumentis. 



" Ille igitur qui tot provinciarum confinia lustravit, tot 

 scientiarum fines propagavit, a nostra praesertim Aca- 

 demia, cuius alumni totiens ex eodem studiorum campo 

 laureas reportarunt, ea qua par est reverentia hodie ex- 

 cipitur. Qui Academiae nostrae nemora, et iuventutis 

 Academicae ludos et certaraina iampridem admiratus est, 

 idem fortasse severiora nostra studia quo melius noverit, 

 eo benignius indies aestimabit. ^'os certe, qui, talium 

 virorum exemplar procul vencrati, etiam nostras inter 

 silvas verum quaeriti?, quanquam hodie nemora ilia nostra 

 gravis umbra contristat, tamen inter ipsas lacrimas non 

 sine gaudio virum magnum vidistis, quaque solatia bene- 

 volentia laudatum audivistis. 



" Vobis igitur praesento Academiae Berolinensis Pro- 

 fessorem illustrem, Hermannum Ludovicum Ferdin- 



ANDUM HeLMHOLTZ." 



The Society of Telegraph Engineers are to give a 

 conversazione in honour of the distinguished electrician 

 at University College, Gower Street, on the evening,' of 

 theilthinst. The large library and entrance hall will be lit 

 up by electric light, and it is hoped there will be a full 

 display of all the recent novelties in electrical science. 



As might have been expected, there was a distinguished 

 audience on Tuesday evening to listen to Prof. Helmholtz 

 at the Royal Institution. Prof. Roscoe, the President of 

 the Chemical Society, in introducing the lecturer, made 

 the following remarks : — 



" Ladies and Gentlemen, Fellows of the Chemical So- 

 ciety — The cordial welcome which you have just given to 

 Prof. Helmholtz shows me that he needs no formal 

 introduction at my hands. His name is honoured wher- 

 ever science is valued, and both his face and his voice 

 arewell remembered in this room. It may therefore 

 suffice if I say that eminent as an anatomist, as a physio- 

 logist, as a physicist, and as a mathematician, we chemists 

 are now about to claim him also as our own. 



" Prof Helmlioltz, in the name of the Chemical Society, 

 and on behalf of its Fellows here assembled, I beg to 



{April T, 1 88] 



welcome you amongst us ; I have the honour to present 

 you with the Faraday Medal of the Society, and to 

 request that you will favour us with your lecture, to 

 which we shall all listen with pleasure and profit." 



Tlie Faraday Lecture'^ 



The majority of Faraday's own researches were con- 

 nected, directly or indirect!)', with questions regarding 

 the nature of electricity, and his most important and 

 most renowned discoveries lay in this field. The facts 

 which he has found are universally known. Never- 

 theless, the fundamental conceptions by which Faraday 

 has been led to these much-admired discoveries have not 

 been received with much consideration. His principal 

 aim was to express in his new conceptions only facts, 

 with the least possible use of hypothetical substances and 

 forces. This was really a progress in general scientific 

 method, destined to purify science from the last remnants 

 of metaphysics. Now that the mathematical interpre- 

 tation of Faraday's conceptions regarding the nature of 

 electric and magnetic force has been given by Clerk 

 Maxwell, we see how great a degree of exactness and 

 precision was really hidden behind his words, which to 

 his contemporaries appeared so vague or obscure ; and it 

 is astonishing in the highest degree to see what a large 

 number of general theories, the methodical deduction of 

 which requires the highest powers of mathematical analysis, 

 he has found by a kind of intuition, with the security 

 of instinct, without the help of a single mathematical 

 formula. 



The electrical researches of Faraday, although em- 

 bracing a great number of apparently minute and discon- 

 nected questions, all of which he has treated with the 

 same careful attention and conscientiousness, are really 

 always aiming at two fundamental problems of natural 

 philosophy, the one more regarding the nature of physical 

 forces, or of forces working at a distance ; the other, in 

 the same way, regarding chemical forces, or those which 

 act from molecule to molecule, and the relation between 

 these and the first. 



The great fundamental problem which Faraday called 

 up anew for discussion was the existence of forces work- 

 ing directly at a distance without any intervening medium. 

 During the last and the beginning of the present century J 

 the model after the likeness of which nearly all physical I 

 theories had been formed was the force of gravitation \ 

 acting between the sun, the planets, and their satellites. 

 It is known how, with much caution and even reluctance. 

 Sir Isaac Newton himself proposed his grand hypothesis, 

 which was destined to become the first great and im- 

 posing example, illustrating the power of true scientific 

 method. 



But then came Oerstedt's discovery of the motions of 

 magnets under the influence of electric currents. The 

 force acting in these phenomena had a new and very 

 singular character. It seemed as if it would drive a 

 single isolated pole of a magnet in a circle around the 

 wire conducting the current, on and on without end, never 

 coming to rest. Faraday saw that a motion of this kind 

 could not be produced by any force of attraction or 

 repulsion, working from point to point. If the current 

 is able to increase the velocity of the magnet, the magnet 

 must react on the current. So he made the experimeiit, 

 and discovered induced cuirent^; he traced them out 

 through all the various conditions under which they 

 ought to appear. He concluded that somewhere in a pait 

 of the space traversed by magnetic force there exists a 

 peculiar state of tension, and that every change of this 

 tension produces electromotive force. This unknown 

 hypothetical state he called provisionally tf e electroto- 

 nic state, and he was occupied for years and years in 



* Abstract prepared by the author. 



