percentage of the sun’s rays (its luminous portion, for 
example) would be re-transmitted. To explain electrical 
phenomena, M. Flammarion remarks, “It is admitted, first, 
that electricity is a subtle fluid capable of being amassed, 
eondensed, and rarefied, &c.,” and on p. 493, “ The Saint 
Elmo fires are a slow manifestation of electricity, a quiet 
outflow, like that of the hydrogen in a gas-burner.” At 
the present day we hardly expected to find so material a 
conception of electricity put forth, unguarded by a restric- 
tion of the fluid theory being merely a convenient hy- 
pothesis whereby electrical effects can be represented to 
the mind. And what evidence has M. Flammarion for 
his unqualified assertion on p. 427, that “the globe is one 
vast reservoir for this subtle fluid [electricity], which exists 
in all the worlds appertaining to our system, and of which 
the radiating focus is in the sun itself... . Its palpita- 
tions sustain the life of the universe !” 
We have noticed a few other passages that have es- 
caped the editor’s attention in the present edition. The 
author speaks of a mist in the Grotto del Cane as “com- 
posed of carbonic acid gas, which is coloured by a small 
quantity of aqueous vapour.” This is difficult to under- 
stand, the vapour being as invisible as the gas itself. We 
did not know it was necessary to use a “preparation of 
‘Joseph’s paper,” steeped in a solution of starch and 
potassic iodide, in order to detect ozone. In describing the 
discovery of oxygen and the chemical composition of the air, 
Lavoisier is theonlyname mentioned. It is not unlikely that 
a French writer should forget Priestley and Scheele, but 
the English editor ought hardly to have overlooked their 
names. We think also that a table of the analysis of air 
obtained from different parts of the globe should have 
been supplied. All that is given is one comparatively 
rough determination, namely, that 100 parts of air con- 
tain 23 of oxygen and 77 of nitrogen by weight. This is 
termed “an analysis made with every conceivable pre- 
caution.” A large part of this same chapter is devoted to 
impurities present in the atmosphere, but Dr. Angus 
Smith’s classical researches are not referred to, nor even 
is his name mentioned. And this reminds us that the 
volume is incomplete without an index, which it ought 
to possess. 
We should like also to have seen some attempt at a 
collation of meteorological phenomena, Meteorologists 
in general seem to have their eyes so close to their special 
observations, that they accumulate a vast mass of figures 
without “ hunting for a cycle,” which has been asserted to 
be their first duty. There certainly appears to be some 
traces of an eleven-yearly cycle in the recurring period of 
extremely hot summers and cold winters from 1793 to the 
present time, cited by M. Flammarion. By collecting and 
tabulating these figures (given in chapters 4 and 5 of the 
third book), it becomes evident that extreme winters have 
immediately preceded or followed very hot summers. 
As the dates stand, they go alternately before and after, 
but this, no doubt, is but an accidental coincidence. 
In spite of the slight defects we have pointed out, 
almost inseparable from a work dealing with such a 
variety of subjects, we can nevertheless endorse the opi- 
nion of the editor that the volume “will be found to be 
readable, popular, and accurate, and it covers ground not 
occupied by any one work in our language.” 
W, F. BARRETT 
NATURE 
Ree 
' + 
[May 8, 1873 
OUR BOOK SHELF 
Mensuration 4 Lines, Surfaces, and Volumes. By 
D. Munn, F.R.S.E. (132 pp. “ Chambers’s Educational 
Course.”) 
THis little work presupposes that the student has some 
knowledge of algebra and geometty, and we agree with 
the author that “it is not until a pupil has acquired this 
knowledge that he can take up the subject with any 
degree of intelligence or derive any educational advantage 
from its study.” The number of propositions (59) is not 
too great ; great judgment is displayed in the selection of 
the properties elucidated ; the proofs are concise and 
clear, and are followed up by more than 350 examples, 
which appear to be clearly drawn up and to be well suited 
to test the student’s acquaintance with the text. The 
book-work is accurately printed, the most important 
mistakes being p. 41, line 23, p. 91, lines 23, 24, and 
p. I10, line 22, but these are easily corrected. The work 
is one of a series, and the references throughout are to 
the edition of Euclid brought out by the same publishers ; 
this reference to Euclid may appear objectionable in the 
eyes of some readers, but it is an objection easily got over 
in the case of those students for whom the work is in- 
tended, 
Geological Stories, Aseries of autobiographies in chrono- 
logical order. By J. E. Taylor, F.G.S, (London : 
Hardwicke, 1873.) 
THE mere form into which Mr. Taylor has thrown his 
work—that of making a characteristic specimen from 
each geological formation tell its own story—has not, we 
think, added anything to its attractiveness: on the con- 
trary, it will be apt to give many readers an uncomfortable 
feeling of unreality, and seems to us to have often cramped 
the author’s freedom of description. We do not object 
to the autobiographical form in the abstract, but we 
think the direct form would have been more suited 
to Mr. Taylor’s mental make. Notwithstanding this little 
drawback, Mr. Taylor tells the “old, old story,” on the 
whole, in a manner well calculated to interest general 
readers, and send them to works where they may get the 
outline here given filled up. Anyone who reads this book 
carefully, will have a very fair notion indeed of what the 
best geologists think has been the earth’s geological 
history. Mr, Taylor has of course wisely avoided enter- 
ing upon disputed points, though one cannot but see that 
he has a comprehensive and very thorough knowledge of 
his subject. The illustrations are plentiful, though many 
of them seem well worn, On the whole the work is one we: 
would recommend to be put into the hands of anyone 
who needs to be enticed into a knowledge of geology- 
“ Stories ” of this class are becoming more and more com= 
mon every year, Not that we think or desire that they 
should ever supersede “ stories ” of another kind ; but we 
take it as one of the most significant signs of the permea- 
tion of culture through society, that books of this class 
find a remunerative public. 
LETTERS TO THE EDITOR 
[Zhe Editor does not hold himself responsible for opinions expressed: 
by his correspondents, No notice is taken of anonymaus 
communications. | ; 
Originators of Glacial Theories 
THE writer of a notice of Tyndall’s “Forms of Water” (NATURE; 
vol. vii. p. 400) blames Tyndall for,having"revived in a popular- 
work the Forbes-Rendu controyersy, and for'calling attention to, 
the claims of Agassiz and Guyot.’"‘  ° 
It seems rather curious that, the attempt to give credit to. — 
scientific investigators for the share they may have had in the- 
development of a great theory should be the occasion of fault- 
finding. No property: is “as’ subtle’ as’ scientific property, and 
the care Tyndall has bestowed upon the historical facts bearing 
eG 
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