( 54 § ) 
[September, 
ANALYSES OF BOOKS. 
Spectrum Analysis in its Application to Terrestrial Substances, 
and the Physical Constitution of the Heavenly Bodies. 
Familarly explained by the late Dr. H. Schellen. Trans- 
lated from the third enlarged and revised German edition, 
by Jane and Caroline Lassell. Edited, with Notes, by 
Captain W. de W. Abney, F.R.S. Second Edition. 
London : Longmans, Green, and Co. 
A work on Spedtrum Analysis may be either devoted to a 
description of the various forms of ihe spedtioscope, and the 
precautions to be observed to ensure success in their employ- 
ment, or it may discuss the results obtained in various sciences 
by the use of this instrument. The volume before us to a certain 
extent combines both these features. At least to a very full 
explanation of the fundamental principles upon which spectrum 
analysis is founded, and to an account of most of the existing 
types of the speftroscope, it adds an elaborate exposition of our 
present knowledge in what may be termed celestial chemistry . 
On the contrary, the reader who seeks for information on the 
use of the spearoscope in organic chemistry, or in biology, will 
find comparatively little to suit his purpose. As an important 
feature— not to be found in many physical treatises — may be 
noted, with approval, the very sparing use made of mathematical 
formulae. Too many writers on such subjects, we fear, instead 
of using such formulae merely where and in so far as it may be 
necessary for explanation, invert the matter. They seek to make 
phenomena merely a peg on which to hang a maximum of ma- 
thematical discussion. By so doing they succeed to a marvel in 
making themselves unintelligible to all save specialists. 
The present work is divided into eight parts. The first part 
discusses the artificial sources of high degrees of light and heat, 
such as the Bunsen burner, the electric spark, the voltaic arc, 
&c. The second bears the heading “ Spectrum Analysis in its 
Application to Terrestrial Substances.” But it includes also the 
theory of light, an account of refraction of the solar spectrum, 
and of the dispersion of light. It would be needless to enume- 
rate the different kinds of spectroscopes which are here described 
and figured. Only eight pages are devoted to the absorption of 
light by liquids, and the micro-spedtroscope is treated much more 
briefly than in Mr. Suffolk’s little work. 
