REYIEWS. 
185 
MESSES. LONGMAN’S TEXT-BOOKS: ARITHMETIC AND 
MENSURATION.* 
A LL Messrs. Longman’s series of text-books are excellent, and the present 
-FI- one is by no means an exception to this good rule. It is, if anything, 
rather better than some of the others in the one respect of style. It is 
remarkably clear and to the point, while in some respects it resembles 
Bishop Colenso’s scientific works, in that no intermediate stage is left out. 
Of course it is not simply an ordinary book on arithmetic. The mere 
elementary matter is much of it omitted. Nevertheless it is a work which 
the schoolboy can readily understand, and one which we should think he 
would be improved by, and at the same time which he would like, from 
the earnest simplicity of its style. The particulars of the work are as 
follows : The first is the division of fractions into two marked periods, the 
rule of greatest common measure being placed in the latter division. The 
second is the (( finding the cube-root by substitution in a simple and easily- 
remembered formula, in preference to giving the rule for extracting the 
root, a rule which can hardly be understood or remembered by any person 
unacquainted with algebra.” The third portion consists in the introduction 
of a chapter on mechanical work. This the author considers somewhat a 
bold step on his part, but he thinks it by no means out of the way in a 
book which is to be read, as the present one is, by mechanics. For our- 
selves, we deem it a capital deviation from the ordinary plan, and we think 
the author is to be praised for his departure from existing ways. The 
treatise on mensuration is a good one, and the examination-papers will be 
found useful by the student. 
SPECTRUM ANAL Y SIS. t 
A SSUREDLY" scientific men did not require such a volume as that which 
now lies upon our table. "What with Roscoe’s work in English, and 
the various foreign contributions to the science of spectroscopy which are 
extant, they had more than enough of works of reference. Yet is the 
present an admirable essay, and one which it would have been discreditable 
to our popular taste to have left untranslated. It is not essentially a 
scientific book — a work of reference for the worker at the spectroscope — but 
it is in the highest degree a book -vyhich w iH do much to popularise the 
pursuit of spectroscopy. For it is remarkably clear and intelligible, and 
it includes so much general information in connection with the subject, 
that we do not see why it may not be easily read, and read with profit, by any 
* u Technical Arithmetic and Mensuration.” By Charles W. Merrifield, 
F.R.S., Principal of the Royal School of Naval Architecture. London : 
Longmans, 1872. 
t “ Spectrum Analysis in its Application to Terrestrial Substances, and 
the Physical Constitution of the Heavenly Bodies Familiarly Explained.” 
By Dr. PI. Scheller, of Cologne. Translated from the Second Edition by 
Jane and Caroline Lassell. Edited, with notes, by William Huggins, 
LL.D., F.R.S. London : Longmans, 1872. 
