SCIENCE. 
203 
or cats, the Satanos of Colden and the Shawanons of later 
writers were one and the same people. These several tribes 
were then followed with the minutest care, so far as the early 
writers throw any light upon the subject. The latter part 
of the paper was a detailed account of the wars, treaties and 
fortunes of this people from 1755 to the present day. The 
discussion upon Mr. Royce’s communication was partici- 
ticipated in by Colonel Garrick Mallery and Major J. W. 
Powell. 
Hr. Hough's paper related to the influence of the inheri- 
tance of knowledge and character as making progress in 
civilization possible. Each individual and each race is the 
outcome of all those material and psychical causes which 
have co-operated to bring them into existence. These facts 
were used by the author to show that the civilization of our 
race cannot be forced upon another race. By a multitude 
of examples Mr. Hough illustrated the methods by which 
the causes which give rise to races and phases of culture 
are brought together and co-operate to their end. The 
paper was discussed by Mr. Lester F. Ward, Major J. W. 
Powell, Professor O. T. Mason and Colonel Garrick Mal- 
lery. 
THE PRIORITY OF THE LATE FRIEDRICH 
MOHR IN REGARD TO THE PRINCIPLE OF 
THE CONSERVATION OF ENERGY. 
By Dr. Geo. W. Rachel. 
In an interesting essay entitled, “ On the History of 
Forces,” published by Dr. C. K. Akin in the P hilosophical 
Magazine, 1 occurs the following passage : 
“ There has been of late a good deal of controversy re- 
garding the priority of invention or discovery of this last 
named principle [Correlation of Forces] and it may be inter- 
esting, in a historical point of view, to take cognizance of 
passages of much earlier date than hitherto relied upon as 
establishing such priority, and upon which I have in the 
majority of cases rather accidentally lighted.” 
The controversy alluded to by Dr. Akin in the passage 
quoted, may be said to have continually attracted the atten- 
tion of scientists since the above reference was made to 
it sixteen years ago. It is well known that Tyndall’s 
authoritative statement of Dr. Robert Julius Mayer’s 
priority has been accepted almost universally since it first 
appeared. 
And yet there always was a number of scientific men 
who held another opinion; but in spite of their protests, even 
to-day the authority of Tyndall prevails, and the popular 
notion all over the civilized world is that Mayer first dis- 
covered and proclaimed the great 'principle in question. 
This view, however, is erroneous, and in this paper the writer 
intends to prove, by the introduction of documentary evi- 
dence, that the late Prof. Fr. Mohr, of Bonn, was the first 
who, in clear and unmistakable language, proclaimed the prin- 
ciple of the “ correlation of forces ” and the “ mechanical theory 
of heat” on which it is based. 
The history of the essay, on which his claim of priority in 
this matter rests, is a peculiar one, and since the circum- 
stances attending its loss and its re-discovery have had a 
direct bearing on the controversy in question, they are 
worth mentioning. 
It is certainly a unique occurrence, that a scientist should, 
for a period of thirty years, have been absolutely unaware 
of the fact that an article which for the first time in the his- 
tory of science states a principle of the utmost importance, 
had actually been published in one of the scientific periodi- 
cals to which he sent his MS ; and this was due only to the 
failure, on the part of the publisher or the editor, to transmit 
a copy of the number containing the paper to the author. 
But this is what really happened in the case of Prof. 
Mohr’s article “ On the Nature of Heat.” 
1 Phil. Mag., 4th series., vol. XXVIII., No. J91, December, 1864 ; pp. 
470-477. 
Mohr first sent it to Poggendorff, but the latter declined 
its publication for the peculiar reason that “ it did not contain 
any new experimental researches. ” 1 2 It was therefore returned 
to Mohr and by him, in turn, sent to Prof. Baumgartner, 
at Vienna, who, at that time (1837), in conjunction with Dr. 
Von Holger, published and edited his Zeitschrift fitr Phy- 
sik und Verwandte Wissenschaften. Not being informed by 
these gentlemen what had been done with the paper, he 
supposed it to have been shelved by them on grounds 
similar to those which prompted Poggendorff’s refusal. 
It was only by an accidental reference to this essaj r in one 
of his later works 3 that he chanced to hear of it again. 
Dr. Akin wrote to him that it had been published bv 
Baumgartner and von Holger, in the fifth volume of their 
Zeitschrift, etc., p. 419, a passage of it having been quoted 
by him [Dr. A.] in the essay refered to above. 
The files of this magazine — which had a very limited 
circulation — having become scarce, since, shortly after 
its publication had ceased, the publishing firm was 
dissolved, it was very difficult to procure a complete 
set. Thus it was that Mohr had to wait many months un- 
til, in response to a request, he received a copy of the 
volume in question, sent for temporary use only by the 
librarian of the Vienna Polytechnic School, Prof. Hlasiwetz. 
A letter, accompanying it, contained the following pas- 
sage : 
“ .... I am happy to be able to congratulate you 
on this important essay, which puts your piiority in regara 
to the question of the mechanical theoiy of heat beyond any 
doubt. I am glad furthermore that I should have been instru- 
mental in the re-discovery of this hidden treasure 4 . . . .” 
Very soon after Dr. Adolph Barth, of Leipzig, the pres- 
ent editor of Poggendorff s Annalen, succeeded in hunting 
up a full set of files of the Zeitschrift, etc., and presented 
them to Prof. Mohr. 
Since then the paper in question has been twice re-pub- 
lished in full. The first time by the author himself in one 
of his later works, with an explanatory statement, contain- 
ing the history of its loss and re-discovery as given above, 6 
and again by Dr. Hermann Klein in the seventh volume 
of his scientific monthly, the “ Gsea ” in the j'ear 1871. 
Although Mohr has never pressed his claim to priority, 
it is certainly due to his memory that all the facts in con- 
nection with it should become fully known. It is always 
to be regretted, when personal considerations — not to say 
animosities — come into play in such questions ; but it seems 
as if this very matter had been destined to be the sub- 
ject of an unceasing feud which has at times even taken 
the shape of a personal quarrel. Only a few years ago 
Prof. Duhring was ‘ dismissed ’ from Berlin University by 
a vote of the faculty, because he had accused Prof. Helm- 
2 For the same reason it was that the editor of the great Annalen de- 
clined five years later the publication of Dr. Mayer’s paper on the same 
subject, and it therefore appeared in Liebig’s Annalen der Chemie 
(42, 240.) 
3 Mechanische Theorie der chemischcn A ffinitat, Fr. Vieweg ; 
Braunschweig , 1868. 
4 The letter bears date of Oct. 17, t868, so that the author received and 
first saw the article fully thirty-one years after its publication. 
5 Allgemeine Theorie der Bewegung und Kraft, etc. Fr. Vieweg, 
Braunschweig , 1869, pp. 80-106. 
Note. — It is to Mohr, and the fate of this essay, that Dr. Akin refers 
in a passage contained in his latest letter to Prof. Stokes, which was 
published in No. is of “ Science.” On page 179 of this Journal he says : 
“ Another [Mohr] who started similar ideas about the same time, having 
been repulsed in one quarter (Pogg. Ann.) took it for granted that the 
same had happened to him also in another (B. & v. H. Ztschr.f. Phys., 
&c.) where it was not the case, so hopeless did he consider his endeavor 
to obtain a hearing.” 
It is a strange coincidence that the same humiliating experience was 
reserved for the last months of the great man’s life. _ For, the last three 
essays which he wrote, each one of them, abounding in new and original 
ideas, were also declined by the editors of “Liebig’s Annalen.” This 
unwarrantable procedure so disgusted the family of the venerable philoso- 
[ pher that they decided after his demise not to publish them in Germany 
at all. They have honored the writer by intrusting to him the publica- 
tion of these valuable essays, and the leaders of “Science” will soon 
I have opportunity to judge, for themselves, of the new and striking views 
advanced by this great thinker. 
