Fuly 14, 1870] 
NATURE 
211 
through some omission, not easily to be explained, if it be not 
the effect of a mere accident, geographical proficiency has never 
hitherto been adequately encouraged. Consequently, the Geo- 
graphical Society has thought it right to step in to supply the 
needful encouragement. ‘There is another good reason for the 
interference of the Society, in the fact that facilities of travel have 
rendered our interests much more cosmopolitan than formerly, 
while the public schools of the old-established type, have made 
no corresponding change in their curriculum. Mere youths 
now-a-days have exhausted the grand tour of two generations 
back, and a year or two of early manhood is often spent in 
America, Australia, and India, while books of travel load our 
library tables. It seems monstrous that a so-called liberal 
education should not qualify men to journey themselves, or to 
read the journeys of others, in an intelligent manner. 
Mr. Wilson remarks, and his remark deserves respect, that 
the masters of Rugby were almost unanimous in rejecting the 
invitation of the Geographical Society, but I can fairly retort 
that other scholars no less practised in education and no less 
competent to decide, pronounced our system of prizes to bea 
valuable and much-needed institution. 
It would be easy to write at great length in support of what 
we have done, and I might perhaps be expected to say something 
on the respective objects of the political and physical geography 
prizes, but I do not wish to provoke a discussion in your pages, 
because I am on the point of going abroad and should be unable 
to take further part in it. FRANCIS GALTON 
“ Kinetic’ and *‘Transmutation” 
I. WHEN, in 1864, I wrote for the Reader the history of the 
Baconian Philosophy of Heat, I found in use, in connection with 
the subject, the term ‘‘ dynamical theory of heat,” in English, 
which was employed as an equivalent for the expression ‘‘ me- 
chanische Warmetheorie,” current in German. The word ‘‘dy- 
namical,” already so vague from frequent abuse, corresponded but 
little, when used in its proper meaning, to the real intent of the 
theory in question ; and the same remark applies, with at least 
equal force, to the word ‘‘mechanisch,” even wider in its scope and 
as often misused. I was thus led to adopt the word ‘‘ Kinetic,” 
to supersede the above; and that in preference to the current 
word, ‘‘cinematic,” which, in conjunction with ‘‘ theory,” would 
imply a tautology. 
I am glad to see that Sir W. Thomson and Professor Tait, in 
their treatises on Natural Philosophy and on Heat, as well as 
in some remarkable papers on Atoms which have appeared in 
NaTurRE, frequently make use of the same word, ‘‘ Kinetic,” 
in connection with the theory of heat and of gases, as also in 
conjunction with ‘‘ energy.” Instead of the expression, ‘‘actual 
energy,” originally introduced, I believe, by Mr. Rankine, Sir W. 
Thomson and Mr. Tait employ the term ‘‘ Kinetic energy ;” and 
from various motives, linguistic as well as strictly scientific, 
I venture to think that the original wording of Mr. Rankine 
in the case of “‘potential energy,” should be likewise super- 
seded, viz., by ‘“‘dynamic energy.” 
2. In the Philosophical Magazine, \have been rated, indirectly, 
by Professor Challis, (for no mention is made of my name in 
connection with the subject), for having applied the word “‘ trans- 
mutation” to rays, without recalling the fact of his having done 
so before me. I considered the expression “ transmutation of 
rays” as the abbreviated and thoroughly English rendering of 
the words, ‘‘ change of the refrangibility of rays, or light,” used 
by Professor Stokes; and as such, requiring no authority but 
the precedent furnished by the existence of the analogous ex- 
pression of ‘‘ transmutation of matter.” If, however, an authority 
had to be cited, it would have been Euler, in whose ‘‘ Nova 
theoria lucis et colorum” (Opusc. var. argum.) the following pas- 
sage occurs :—‘‘Cum igitur a corporibus rubris radii tantum 
rubri, et a violaceis violacei ad nos pertingant, etiamsi radii albi 
in ea incidissent, manifestum est istam transmutationem a sola 
reflectione proficisci non posse.” 
As I have returned to this subject, I may be permitted to ex- 
press my astonishment that Professor Challis, who thought it 
due to him that his name should be mentioned for being the 
author of the expression “transmutation of rays,” should have 
on his part omitted, in speaking of the transmutation of Her- 
schelic rays into Newtonic, a reference to my own share in the 
res geste. WNhen I see the same thing being done in so widely cir- 
culated a treatise as that of Mr. Brooke on Natural Philosophy, 
and in one intended for even more popular reading, reproducing 
the teaching of the Polytechnic, I might think of entering a 
protest, if experience had not convinced me of its uselessness. 
C. K. AKIN 
Parturition of the Kangaroo 
I BEG leave to call your attention to certain comments in your 
issue of the 23rd of June on the proceedings of the last meeting 
of the Royal Geological and Zoological Societies of Ireland. It 
is usual when parenthetical observations are made in any journal 
without the customary affix ‘‘ Ed.” to ascribe them to the 
printer's devil. Now, your devil, in commenting on an ifer/ect 
report of your Dublin correspondent, would lead your readers 
erroneously to infer that I had adopted the ideas which he has 
been pleased to call ‘‘ absolute nonsense,” and takes me to task 
for saying ‘‘that the actual passage of the foetal kangaroo from 
the uterus to the pouch was not yet proved;”’ he himself 
stating that my remarks were ‘‘in contradiction to the facts 
observed by the late Earl of Derby’s father or by the present 
Professor Owen.” Now, a critic calling in question the words of 
others should be careful of his own. No facts on the subject 
were observed by the late Earl of Derby’s father, and Professor 
Owen, after elaborate arrangements for the observation, states 
that ‘‘as parturition took place in the night, the mode of trans- 
mission tothe pouch was not observed.” (Phil. Trans. for 1834, p. 
344.) There have been four observers in this matter especially 
worthy of being noticed:—(1) the keeper at the Zoological 
Gardens, Knowsley, who, according to Lord Derby’s statement, 
saw the young kangaroo born, and that it was placed in the 
pouch by the paws of the mother (Proceedings of Zoological 
Society for 1833, p. 132); (2) Professor Owen, as referred 
to above; (3) Mr. E. G. Hill, who, at thirty yards’ distance, 
saw the kangaroo with her mouth take up what he thought was 
a stone, open the pouch with her paws, and place it in the 
marsupium, and that he shot the animal and found a newly- 
born foetus in the pouch (Proceedings of Zoological Society 
for 1867, p. 476); (4) M. Jules Verreaux, who is mentioned 
by M. E. Alix as having seen the kangaroo remove the foetus 
from the vulva with her mouth, and place it inthe pouch (Annals 
of Natural History for 1866, p. 316). These all differ as to the 
actual facts observed, and would seem sufficient to justify me in 
the statement [had made. That Professor Owen does not consider 
the question settled, may be inferred from his concluding observa- 
tions on the subject, ‘‘ whether the circumstance of the partu- 
rition is constant, viz, the dropping on the ground, or whether 
the foetus may occasionally be received by the mouth from the 
vulya, Iam disposed to regard as a matter for further observation ; 
but the main fact of the conveyance of the foetus to the pouch by 
means of the mouth may now be held as the more probable (at 
least the more usual, ifnot the constant) way in the genus Macro- 
pus” (Proceedings of Zoological Society for 1866, page 382). I 
refrain from any comments, but I thought it right to remonstrate 
against statements which I felt were injurious to me, to the 
Society to which I have the honour to belong, and to the ad- 
vancement of science. JouHN Barker, M.D, 
Dublin, July 1 
The Extinction of Stars 
Ir you will kindly permit an amateur to rush in where astro- 
nomers fear to tread, I shall be glad to offer a few remarks on 
the above subject. 
The progress of science enables us to trace, with a probability 
almost amounting to certainty, the career of a star from its 
birth ; from the most diffused condition of its parent nebula ; 
through the stage of primary agglomeration when it shines as 
our sun ; through the process of cooling into a dim and cloudy 
spheroid, such as Jupiter or our earth ; until cold rules supreme, 
and the once glowing orb rolls on, barren as our moon. 
But when we have reached this stage, we have by no means 
done with the star. It must continue on its course, and, though 
in obscurity, it must retain its momentum and its attractive 
force. Our sun will thus one day travel in darkness, attended 
by a cohort of funereal planets, and perpetual night will reign 
over the solar system. This result appears-to be but a question 
of time, and we are, therefore, led to the consideration that 
many systems must, in all probability, be already extinct, and 
wandering unnoticed. But as extinction is a gradual process, 
there will be multitudes of stars in various stages of dimness, 
