204 



SCIENCE. 



holtz of plagiarism (from Dr. Mayer), in the very same 

 matter, and used unbecoming and disrespectful language 

 towards his colleague. 



Prof. Tait also, as our readers are well aware, has re- 

 opened the controversy and has attacked Dr. Mayer and his 

 champion, Prof. Tyndall, in an unnecessarily virulent and 

 aggressive manner. 



It is very likely that both these gentlemen would have 

 acted quite differently in this matter bad they been informed 

 of the fact that Mohr's priority dates back to 1837. Prof. 

 Tait only refers to it in the preface to the second edition of 

 his '' Lectures on some recent advances " &c, * stating that 1 e 

 had, until very shortly before its publication, not seen or 

 heard of Mohr's writings on the subject, whose indis- 

 putable claim to priority he at the same time admits. 



In the beginning of this paper we have given the intro- 

 duction to Dr. Akin's interesting, though as it seems, not 

 very widely known essay, and we shall now proceed to give, 

 in the same order as that adopted by him, the various passages 

 — almost exclusively from Mohr's paper — which Dr. Akin 

 cites in support of his view "that they must invalidate 

 all claims to priority of an earlier date." 



Dr. Akin continues (1. c. p. 473): 



" The following is an extract from Placidus Heinrich's : 

 Die Phosphorescenz drV.. published in 1872: 'Meanwhile 

 we know, at least with a certain degree of reliability, 

 that nothing is lost in Nature .... every- 

 thing may be explained by constant interchange ; the 

 one gains by the loss of the other ; the one takes its origin 

 from the disappearance of the other. Therefore there is no 

 such thing as loss in (he Universe, only change and inter- 

 change.' ' 



The next quotation is from a paper by Dr. Mohr, of 

 Koblenz, " On Heat" published in 1837 : 



'Aside from the 54 chemical elements at present [1837] 

 known, there is but one agency in Nature and this we call 

 Force ; it may under suitable circumstances appear as mo- 

 tion, chemical affinity, cohesion, electricity, light, heat and 

 magnetism, and by means of each of these different forms 

 all the others may be produced. ... If, by the 

 force of your arm you remove an induction-coil from a 

 magnet, an electric cut rent will originate in the surrounding 

 spiral wire (helix), which, on being interrupted, appears as a 

 spark, or if the conducting wire is reduced in size, as a 

 glowing wire {heat and light); it will also magnetize a steel 

 needle if it is conducted through a helix surrounding it ; 

 it will decompose the water it passes through, annihilating 

 its chemical affinity and its cohesion at the same time, and 

 since the thin Platinum-wire, Ampere's helix and the appar- 

 atus for the decomposition of water, may be interpolated at 

 the same time in one and the same chain, it is evident that 

 the force of the human arm may appear under different condi- 

 tions as heat, light, chemical affinity, magnetism and cohesion." 1 



" The passage is followed by two more pages, showing in 

 greater detail the connexion and transmutability of the sev- 

 eral known forces and a transcript or translation of which 

 I [Dr. Akin] hope to give at some future occasion. The 



^McMillan &* Co., London, 1877. 



'. . . Unterdesscn wissen wir wenigstens soviel mit Zuverla'ssigkeit, 

 dass in der Natur nichts veloren geht . . alles erklart sich durch cincn 

 steten 'Jmtausch ; das cine eewinnt durch Verlust des Andcrn: das Eine 

 entsteht durch das Verschwinden des Andern. . . Also im Universum 

 nie Verlust, nur Wcchsel und (Jmtausch. . . iVol. II., s. 283.) 



*. Ausser den bekannten 54 chcmischcn F.lcmcnten gibt es in der Natur 

 der Dingc nur noch ein Agens und dieses heisst Kraft ; es kann unter 

 passendtn Vrrhiiltnissen als Hewtgung, chemische Affinitat, Cohiision, 

 ElectricitUt, Licht, Wiirmc und Magnet sinus hervortrcten, und aus jeder 

 di ser Erschcinungsartcr kiinnen alle librigen hcrvorgebracht werden 



. Vermiige der Kraft des Amies rcisst man die Inductiunstrolle von 

 eincm Magnetcn los. es entsteht in dem ilarum geschlungcncn Schrau- 

 bendrahtc ein electrischcr Strom, welcher bei Untcrbrrchung als Funke, 

 oner bei vcrengerter Leitung als gliihcndcr Draht (W&rme it/r,r Lickt) 

 crscheint ; dcrsclbc erregt marnetitcke I'alaiitiit , wenn cr als Schrau- 

 bendraht um eine Stahlcnadel gcleitet wird ; er zersetzt das Wadset' 

 wodurch er gcleitet wird, und hebt zugleich seine Affinitat und Cohiision 

 auf; und da nun der dlinnc I' atindraht, die Amperesrhe Schrauhc und 



der WaMeRenetzungMpi arai gleichzeitig in dereelhen Kctte eingcschlos- 

 sen >-ein k'inncn, so leuchtct em. wie die Kraft, der Armet untei ■<>- 

 ichiedenen Verhaltnitten ah W&rmt, Licht, Chtmischt Affinitat, 

 Magnrtismw. und Cok&tion turn Vortchein gekommtn ist, (Baumgait- 



nerli Zeitschr. f. I'hysik, &c. Vol. V., s. 442-4 \.) 



author concludes his observations with the following judi- 

 cious remarks : 



' Without any doubt all physical phenomena produced by 

 the so-called Imponderabilia may be classified under one 

 of these heads . . . But there remains an immense 

 amount of labor to be done, before, starting from this pass- 

 ing suggestion, we shall arrive at a complete insight into the 

 nature of these things. 3 



"With regard to heat, besides showing that its nature or 

 form is motion, which is the principal object of the paper, 

 the writer states (p. 422) : 



'What . . . annuls (destroys) a force, must itself be 

 a force.' 4 



"And again (p. 422) : 



'What . . . produces (causes) a force must itself be 

 a force.' 5 



Whence he concludes, considering the effects of heat 

 (p. 421): 



' Heat appears as a force in innumerable cases. 6 



"Considering the remarks of Placidus Heinrich as a casual 

 generalization which is found in the writings of other 

 authors of the last century and the beginning of the present 

 (Rimford, Davy. Faraday and others), and consider- 

 ing furthermore the fact that Mohr's object was to 

 show that heat is not imponderable matter, but o nsists 

 of the oscillator}' motion of ponderable matter, and to 

 prove that this is the case with all the other Imponderabilia 

 so-called, and that because all of the latter, are intro- 

 convertible and convertible into forces, we are justified, nay 

 even forced \>y irresistible logic to declare all these agen- 

 cies — forces as well as motions — to be different manifesta- 

 tions of one and the same thing, it is established beyond any 

 doubt that Friedrich Mohr was the first who in clear and 

 convincing language stated the great principles in question. 



"This does, of course, not detract from the merit of 

 Mayer or Helmholtz, or any other author who has arrived 

 independently at similar conclusions, and no one is more 

 ready than Mohr himself to give credit to whom it is due. 

 In the explanatory statement given with the reprint of the 

 essay, he quotes Tyndall's reference to Dr. Mayer's 

 paper mentioned above and indorses the praise contained 

 in it with all his heart. He says : 



" I fully accept this statement by Tyndall. The laying 

 down of the mechanical equivalent of heat is one of the 

 principal points in this matter, but it does not exhaust it. 

 Mayer had stated it and calculated it from known facts to 

 be 365 Kilogrammometers. That this figure is not the 

 same we now adopt (424 KM.), does not detract from 

 Mayer's merits in the least ; the foremost thing was to lay 

 down the principle that mechanical motion has its equivalent in 

 heat, that one originates from the other, that both are therefore 

 equivalent to wit : motions. 1 



" But he continues : 

 jj ,',' While thus with all my heart recognizing the great merits 

 of Mayer (and Joule), I would be unjust towards myself 

 if I should pass in silence over my former writings, which 

 by peculiar circumstances have not become generally 

 known. 8 



* In his reprint, Mohr remarks that at most places where the word 

 " Kraft " was used in this first essay, he would now have " Bewegung." 

 — R. 



3 . Ohne Zweifel lassen sich alle physikalischen Erscheinungen der 

 sogenannten Imponderabilien unter einer dieser Rubriken bringen. . . 

 Es bleibt aber von dieser fUichtigen Andeutung bis zur vollkommen Ein- 

 sicht in die Natur der Sache noch unendlich viel zu thun iibrig. (s. 445.) 



4 . Was . . eine Kraft aufhebt, muss sclbst cine Kraft* sein. 



6 . ' Was . . eine Kraft hervorbringt, muss selbsl eine Kraft sein. 

 ". Die Warme erscheint in unziihligen Fallen als eine Kraft. 



7 . Ich acccptirc dicse Acusserung von Tyndai.i. vollstandig. Die Aufs- 

 tcllung des mechanischen A equivalentes der W&rme 1st ein Haupttheil 

 der ganzen Lehre, aber es crschiipft sie nicht. Maykk hattc (Limit's 

 Ammlcn, 42, 240) d; s Aeciuivalent ausgesprochen und aus bekannten 

 Thatsachen zu Kilogrammometern bercchnet. Dass dicse Zahl nicht 

 dicselbe ist die wir icizt annehmen (424 KM.)benimmt dem Verd.enste 

 Mayer's nicht das Gcnngste ; die Hauf-tsa, tie war die A uj 'stellung dtt 

 Salzes dass die meckanische Bewegung ein A equivalent in der Warme 

 habe, dass eines aus dem andern entstehe dass beide also gieichartig 

 sind nam lieh Btlvegung. (s. 80.) 



h . Indent ich die grosscn Verditnste Mayer's (und Joule's) in diesen 

 Zweige der Wissenschaft mit vollem Herzen anerkenne, wlirde ich gegen, 

 mich selbst cine Ungerechtigkeit begchen, wenn ich nicht meine fruhcren 

 Arbeiten, die durch einer. besondern Umstand nicht zur allgemeinen 

 Kcnntniss gekommen sind, stillschweigand ubcrgchen wollte. (s. 82,) 



