204 
SCIENCE. 
holtz of plagiarism (from Dr. Mayfr), in the vrry 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. Tyndai.i., in an unnecessarily virulent and 
aggressive manner. 
It is very likely ihat both these gentlemen would have 
acted quite differently in this matter had 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 ” & V.,* 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 Phosphorescent published in 1872: ‘Meanwhile 
we know, at least with a cerlain 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.’ 1 * 
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. 
*. . . Unterdessen wissen wir wenigstens soviel mit Zuverlassigkeit, 
dass in der Natur nichts veloren geht . . alles erklart sich durch einen 
steten Umtausch ; das eine eewinnt durch Verlust des Andern : das Eine 
entsteht durch das Verschwinden des Andern. . . Also im Universum 
nie Verlust, nur Wechsel und Umtausch. . . tVol. II., s. 283.) 
2 . Ausser den bekannten 54 chemischen Elementen giht es in der Natur 
der Dinge nur noch ein Agens und dieses heisst Kraft; es kann unter 
passenden Verhaltnissen als Bewtgung, chemische Affinitat, Cohasion, 
Electricitat, Licht, Warme und Magnet smus hervortreten, und aus jeder 
di ser Erscheinungsarter konnen allc iibrigen hervorgebracht werden . 
. Vermoge der Kraft des Armes reisst man die Inductionstrolle von 
einem Magneten los, es entsteht in dem darum geschlungenen Schrau- 
bendrahte ein electrischer Strom, welchcr bei Unterbrechung als Funke, 
oner bei verengerter Leitung als gliihender Draht (Warme und Licht ) 
erscheint ; derselbe erregt mngnetische Palaritiit , wenn er als Schrau- 
bendraht um eine Stahlenadel geleitet wird ; er zersetzt das Wasser 
wodurch er geleitet wird, und hebt zugleich seine Affinitat und Cohasion 
auf ; und da nun der diinne P atindraht, die Amp^resche Schraube und 
der Wasserzeri-etzungsaprarat gleichzeitig in derselben Kette eingeschlos- 
sen sein konnen, so leuchtet ein, 7 vie die Kraft , der Armes unter ver- 
schiedenen Verhaltnissen als Warme, Licht , Chemische Affinitat , 
Magnetism us und Cohasion zum Vorschein gekommen ist, (Baumgart- 
ner’s Zeitschr. f. Physik, &c. Vol. V., s, 442-43.) 
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 * 7 
Whence he concludes, considering the effects of heat 
(p. 421): 
‘ Heat appears as a force in innumerable cases. 8 
“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 
(Rumford, 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 by 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 full)' 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 : 
ij 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 fliichtigen Andeutung bis zur vollkommen Ein- 
sicht in die Natur der Sache noch unendlich viel zu thun iibrig. (s. 445.) 
4 . Was . . eine Kraft aulhebt, muss selbst eine Kraft* sein. 
6 . 1 Was . . eine Kraft hervorbringt, muss selbst eine Kraft sein. 
“. Die Warme erscheint in unzahligen Fallen als eine Kraft. 
7 . Ich acceptire diese Aeusserung von Tvndali. vollstandig. Die Aufs- 
tellung des mechanischen Aequivalentes der Warme ist ein Haupttheil 
der ganzen Lehre, aher es erschijpft sie nicht. Mayer hatte I Liebig’s 
Annalen, 42, 240) dss Aequivalent ausgesprochen und aus bekannten 
Thatsachen zu Kilogrammometern berechnet. Dass diese Zahl nicht 
dieselbe ist die wir jeizt annehmen (424 KM.) benimmt dem Verdienste 
M AVer’s nicht das Geringste ; die Haugtsache war die A ujstetlung des 
Saizes dass die mechanische Bewegung ein Aequivalent in der Warme 
habe, dass eines aus dem andern entstehe dass beide also gleichartig 
sind ndmlich Bewegung. (s. 80.) 
B . Indem ich die grossen Verdienste Mayer’s (und Joule’s) in diesem 
Zweige der Wissenschaft mit vollem Herzen anerkenne, wiirde ich gegen, 
mich selbst eine Ungerechtigkeit begehen, wenn ich nicht meine fruheren 
Arbeiten, die durch einer. besondern Umstand nicht zur allgemeinen 
Kenntniss gekommen sind, stillschweigand ubergehen wollte. (s. 82.) 
