210 
NATURE 
[Fuly 14, 1870 
By the side of this first assemblage of facts, of which the 
meaning seems to me not doubtful, I find another of at least equal 
importance—that of meteoric rocks evidently eruptive. 
The meteoric iron recently discovered in the cordillera of Deesa, 
in Chili, having been submitted by me to a careful analysis, both 
chemical and mineralogical, appeared to me clearly to be formed 
from the mixture of two meteoric rocks, known, each of them, 
by masses of which they are entirely constituted. The one, 
stony and black, fell at Sétif, Algeria (June 9, 1867); the 
other, metallic, constitutes the mass of iron found in 1828 at 
Caille, in the south of France. Besides this, the metallic portion 
of the iron of Deesa, in which the black angular fragments are 
encrusted, has manifestly preserved the character assumed by the 
iron of Caille when it is subjected to fusion, so that the mode 
of formation of the Chilian mass cannot be considered doubtful. 
We must believe that on a globe, large enough to have been the 
seat of considerable pressure, masses of iron from Caille, still 
melted, were injected into superposed layers of Sétif rock so as 
to give birth to dykes, identical, except in their mineralogical 
nature, with those which the crust of the earth everywhere 
presents to our view. 
These two orders of facts, which seem to me indisputable, 
being admitted, there remains to explain how fragments of poly- 
genic conglomerates, or of dykes, can wander through space, and 
here only it is that the hypothetic part of my work begins. 
From what precedes the meteorites in question are, by defi- 
nition, planetary fragments. It remains to learn how the rupture 
of the planet whence they come can have taken place. On this 
it is evidently impossible to argue with any certainty. 
Nevertheless, it appears to me that several considerations may 
greatly facilitate a choice among the different explanations which 
present themselves to the mind. 
Inthe first place the zity of composition of the solar system, 
mentioned by Mr, Maskelyne, is evident. 
Secondly, it is manifest that in the same system there exists a 
perfect zzty of geological phenomena. 
Lastly, but this, perhaps, has less weight, it appears to me 
that we should have recourse to accidental causes to explain 
natural phenomena only when every other means is forbidden. 
This said, I observe that without making any other hypothesis 
than that of Laplace, we arrive at the conclusion that the stars 
tend of themselves to become broken. ‘The earth is cracked 
in all directions ; these fissures, designated as faz//s, are known 
to everyone. Little by little, as they form, they become reunited 
by the injection of an internal melted cement. But if the supply of 
this cement failed, the molecular operation which has opened the 
faults would still continue its action to enlarge them; we observe 
this in the moon, which, far more advanced in refrigeration, 
manifests by its fissures a phenomenon hitherto unknown in our 
earth. Evidently if we suppose to have been formed at the same 
time as the moon, a much smaller globe, that globe will have 
arrived actually at a state of cold far more advanced than that 
of the moon; and the fissures, excessively multiplied, and 
increased in depth and in width, may have finished by reducing 
the globe into separate fragments. 
We have no positive proofs that such events have really hap- 
pened, but is it not a very simple hypothesis to admit that 
meteorites, which bear so evidently the impress of a detritic 
character, may have had such an origin ? 
It is very probable that once parted from one another, the 
fragments are scattered along the orbit, and it is evident that they 
will tend progressively to approach the central star, so as to finish 
by falling on its surface under the form of meteorites. 
Now, whether these fragments have been sorted or whether 
they have not, whether this sorting, if it exists, be or be not in 
accordance with that which the facts of observation have seemed 
to point out to me ; I consider the question as entirely secondary 
as regards the general theory, and I request permission, in order to 
keep within the limits of the present discussion, to lay it absolutely 
aside for the present. I will simply repeat, in concluding this 
note, already somewhat long, that positive facts alone have 
served as the basis of my theory, and that the different cireum- 
stances on which my opponent has so learnedly insisted, possess 
fcr me but a secondary importance. 
At the same time, I sincerely congratulate myself in the fact that 
my work has had the good fortune to fix the attention of a scien- 
tific observer so well placed as Mr. Maskelyne for submitting the 
mineralogical and lithological part of it to a severe verification. 
Dr. STANISLAS MEUNIER, Aide Naturaliste au Muséum 
23, rue de Vaugirard, a Paris 
Monographs of M. Michel Chasles 
Par une lettre inséréee dans le No. 36 de NATURE, page 199, 
| M. C. Ingleby fait appel aux lecteurs de votre Revue pour 
obtenir quelques renseignements au sujet de ‘‘l’Apergu histo- 
rique” de M. Chasles, imprimé 4 Bruxelles en 1837. Le travail, 
qui porte pour titre exact : ‘* Apercu historique sur lorigine et 
le développement des méthodes en géométrie, particulierement 
de celles qui se rapportent a la géometrie moderne,” a été publié 
par l’Académie royale des sciences de Belgique dans le tome xi. 
de ses ‘‘ Mémoires couronnés et des savants étrangers’’ (in 4to.), 
et il est trés-difficile aujourd’hui de s’en procurer des exemplaires. 
Toutefois, M. Ingleby pourra s’adresser, pour consulter ce 
mémoire, 4 la Société royale de Londres, qui doit certainement 
le posséder dans sa Bibliothéque. _ Voici d’ailleurs la liste des 
établissements scientifiques de Londres qui ont regu cet ouvrage 
a l’époque de sa publication: Société royale, Société astro- 
nomique, Société royale de littérature, et Société linnéenne. 
Jespére que ces details pourront étre utiles a votre honorable 
correspondant. 
Bruxelles, le 8 Juillet A. LANCASTER, 
Attaché au Secrétariat de l’ Académie royale des 
Sciences de Belgique 
In reply to Dr. Ingleby’s note I may state that many papers 
by M. Chasles on various subjects in the history of Mathe- 
matics, are to be found in the volumes of the Comptes Rendus 
for 1837, onwards. His ‘‘ Apercu Historique” &c., originally ap- 
peared as a special volume of the Transactions of the Brussels 
Academy, but was sold as an independent work. It appeared 
in quarto, and was published in 1837. Like his ‘‘ Traité de 
Géométrie Supérieure,” it is very rare, and fetches an enormous 
price. Mr. Quaritch is, perhaps, the most likely bookseller in 
London to be able to procure it. The German translation by 
Sohncke is comparatively cheap, and may be readily obtained 
through Messrs. Williams and Norgate. 
Torquay, July 9 G, E. Day 
The Specific Heat of Mixtures of Alcohol and Water 
IN the report of the papers read at the Academy of Sciences, 
Paris, June 13, which appears in NATURE for June 30, it is 
stated that MM. Jamin and Amaury presented a note on the 
above subject, in which they point out, apparently as if it were 
something new, that the specific heat of some of these mixtures 
rises even above that of water. 
Now, more than two years ago, March 26, 1868, we com- 
municated a paper to the Royal Society giving the specific heat 
of various mixtures of alcohol and water, and drawing special 
attention to the remarkable fact that the specific heat of these 
mixtures is not only above the calculated mean specific heat, but 
that in all those of less strength than 36 per cent. of alcohol, it 
is higher than the specific heat of water itself. A knowledge of 
this fact should therefore be old by this time. 
An abstract of our paper is printed in Proc. R. S., vol. xvi., 
p- 337. Subsequently we examined this and various other pro- 
perties of similar mixtures more in detail, and communicated 
our results to the Royal Society in a second paper, an abstract 
of which is printed in Proc. R.S., vol. xvii., p. 333, and the 
paper in full in Phil. Trans. for 1869, Part 11, p. 591. 
The insertion of the above in the next number of your valuable 
journal will greatly oblige A. Dupre & F. T. M. PAGE 
Westminster Hospital, July 2 
Geographical Prizes 
HAvina been chiefly instrumental in causing prize medals to 
be offered by the Geographical Society for competition among the 
chief public schools, I do not like Mr. Wilson’s letter in your 
last number to pass without comment. 
Geography may be, to use his words, a subordinate branch of 
education, but I maintain that it is so only in the sense that it 
underlies a large part of liberal knowledge. It underlies the 
study of history. For example, I do not see how a boy could 
thoroughly understand Bible history without having acquired a very 
vivid conception of the geography of Palestine, and the same is 
true for all other histories, ancient and modern. It follows, as a 
matter of fact, that geography is incidentally taught to a consi- 
derable extent in schools, and I am sorry to say it is sometimes 
very ill-taught, as we learn from the reports of our examiners, but 
