i 
1873| 
probably its author himself could have wished. A wrong 
impression of the subject is created by the title, which 
though singularly happy in itself does not fairly describe 
the contents of the book. Such a title suggests an accu- 
rate and luminous discussion of the phenomena of evapo- 
ration and condensation, the growth and movements and 
disappearances of mists and clouds, the formation and 
distribution of rain and the laws regulating the rainfall 
over the globe, the meaning of frost, the birth and history 
of hail and snow, the circulation of water over the land 
with the ways and workings of brook, stream, and river, 
from mountain-peak to sea-shore, the architecture and 
the functions of snow-fields, glaciers, and icebergs—in 
short a kind of scientific poem, dedicated to the glory of 
that grand old element—water. Dr. Tyndall could write 
such a poem better than most men, and indeed it was 
with the expectation that he had attempted it that we 
opened this last volume of his. Out of the 192 pages 28 
are devoted to clouds, rains, rivers, waves of light and 
heat, oceanic distillation and mountain condensers. The 
rest treat wholly of ice. So that if we may judge by the 
relative space devoted to the different forms of water, ice 
must be six times more important than ail the rest put 
together. A less ambitious title, such as its author could 
readily suggest, descriptive of the fact that the book is a 
record of work, intellectual and corporeal, among the 
Swiss glaciers, would prevent the feeling of disappoint- 
ment with which many a reader has no doubt come to 
the last page. 
Dr. Tyndall did not intend, we suppose, that his book 
should be regarded in any other light than as a popular 
exposition of his subject, and would probably disclaim 
any place for it as a contribution of new facts and reason- 
ings to our knowledge of glaciers. His narratives of last 
year’s climbings and observations read very much like 
those of older ones with which he has already made us 
familiar. They are pleasantly written, and will convey to 
a reader, who has never seen a glacier, a picturesque 
notion of what he has missed. But surely it was not 
necessary to rake up again the Forbes-Rendu controversy, 
nor to renew the claims of Agassiz and Guyot. Wecould 
have wished, too, that while alluding to Mr. Mathews 
and other recent observers on ice-structure the writer 
had taken some notice of the attack upon his own theory 
by Canon Mosely and Mr. Croll. 
OUR BOOK SHELF 
Die Anwendung Des Spectralapparate von Dr. K. 
Vierordt. (Tiibingen : H. Laupp, 1873.) 
Dr. VIERORDT has been endeavouring to found a quanti- 
tative spectrum analysis for bodies giving an absorption 
spectrum. 
-divided horizontally into two parts; one of these is ad- 
justed to a certain width ; the solution whose absorption 
is to be examined is placed opposite this, and in front of 
the other half is placed another solution of the same body 
but of a different strength, and the slit is then narrowed 
or widened as the solution is stronger or weaker until the 
absorption is the same in both halves of the spectrum. 
The width of the latter slit is then read off. By using 
a number of solutions of strengths varying decimally from 
the weakest possible to the strongest through which light 
will pass, curves are obtained and a solution of unknown 
NATURE 
His method consists in the use of a slit | 
401 
value ascertained, The solutions to be examined are, of - 
of course, kept at a constant thickness, As the relation 
between the concentration of the solution and its coeffi- 
cient of the absorption of light only remains constant 
within certain limits, solutions of the necessary dilution 
have to be employed and unknown solutions must be 
diluted to this point: the value is then found by calcu- 
lation. ‘ 
Tables for calculations of various kinds required are 
given, and the memoir is illustrated with lithographs of 
the working details of the divided slit. A number of 
specimen curves are also given. The memoir is well 
worthy the attention of all who have to estimate the © 
strength of colouring matter. 
EETTERS TO THE EDITOR 
[The Editor does not hold himself responsible for opinions expressed 
by his correspondents. No notice is taken of anonymous 
communications. | 
Existence of Man in the Miocene 
I HAVE received a letter from Mr. Edmund Calvert, in which 
he informs me that his brother, Mr, Frank Calvert, has recently 
discovered, near the Dardanelles, what he regards as conclusive 
evidence of the existence of man during the Miocene period. 
Mr. Calvert had previously sent me some drawings of bones and 
shells from the strata in question, which Mr. Busk and Mr. 
Gwyn Jeffreys were good enough to examine forme. He has 
now met with a fragment of a bone, probably belonging either 
to the Dinotherium or a Mastodon, oa the convex side of which 
is engraved a representation of a horned quadruped, ‘* with 
arched neck, lozenge-shaped chest, long body, straight fore legs, 
and broad feet.” There are also, he says, traces of seven or 
eight other figures, which, however, are nearly obliterated. He 
informs me that in the same stratum he has also found a flint 
flake, and several bones broken as if for the extraction of 
marrow. ; 
This discovery would not only prove the existence of man in 
Miocene times, but of man who had already made some pro- 
gress, at least, in art. Mr. Calvert assures me that he feels no 
doubt whatever as to the geological age of the stratum from 
which these specimens were obtained. 
Of course I am not in a position myself to express any opinion 
on the subject; but I am sure that the statements of so compe- 
tent an observer as Mr. Calvert will interest your readers. 
High Elms, March 23 Joun Lusbock 
Adaptation to External Conditions 
THE curious modification of adaptation to external conditions 
| in the case of the Sa/amandra atra, which I have more than 
once brought under the notice of naturalists, but which I myself 
first noticed under the direction of Prof. von Siebold, has been 
cited by Mr. Darwin (‘* Origin of Species,” 4th Ed. p. 534) in 
confirmation of his views. I revert to it now for the sake of its 
illustration of a new and striking observation, which has excited 
the incredulity of several eminent naturalists in France—an in- 
credulity, we may suppose, founded on their ignorance of the 
previous observation. ‘The fact to which I called attention was 
this : The ordinary salamanier, or Newt, is born in the watcr 
as a tadpole, and in the water it completes its metamorphosis, 
But the Sa/awandra atra, living high up in the mountains, with 
no pools in which to pass its tadpole existence, is born on the 
land, a completely formed animal ; that is to say it passes 
through the tadpole stage while still within its mother’s body. 
I have taken it from the gravid female in this tadpole state, and 
placed it in water, wherein it swam as if that were its natal ele- 
ment. 
In the Revie Scientifique, No. 37, there has just appeared a 
brief account of some observations made by M. Baray at Guade- 
loupe, from which it appears that the frogs, having in that vol- 
canic island no marshes nor pools suitable for the early tadpoles, 
strength can then be interpolated in the curve and its | have adapted themselves to these conditions by passing through 
