292 
POPULAR SCIENCE REVIEW. 
HELMHOLTZ’S SCIENTIFIC LECTURES * . 
D r. TYNDALL certainly did not err in advising the Messrs. Longmans 
to publish the work which is now before us. For though it is but a 
portion, and that a very small one, of the subject of Natural Philosophy,, 
still it is so charmingly written, and has been translated with so much 
ability by Dr. Atkinson, that we doubt not it will receive a considerable- 
share of attention from educated Englishmen. Of the lectures now trans- 
lated, two have appeared in an English print already, that on the ‘‘Physio- 
logical causes of Harmony in Music,” translated by A. J. Ellis, M.A., F.R.S., 
and on the “Interaction of the Natural Forces,” translated by Professor Tyn- 
dall, F.R.S. The others are entirely new to the English public, and are some 
of them of the highest interest. Of these we may especially mention two — 
that on “ Ice and Glaciers,” translated by the Editor, and that on “ The 
Recent Progress of the Theory of Vision,” which is rendered into English by 
Dr. Pj^e-Smith, B.A., F.R.C.P. These are imquestionably the most in- 
teresting papers in the work, and if we were to say which of the two is the 
most instructive with reference to novelty of facts and record of work done 
by the older writers, we should select Dr. Pye-Smitli’s. But both are full 
of interest, and they are also amply illustrated, and with the other able 
essays they form a volume most creditable to the author, who, a profound 
physicist and physiologist, has descended to the popular level, with the most 
winning style, and with the most happy results. 
ON FOODS.! 
I T is certain that much as has been written on the subject of food there 
is still a great deal of ignorance, even among medical men who are 
placed in the position of medical officers of Health, as to the relative value 
of certain varieties. Knowing this to be the case we hope to see this want 
of knowledge removed by a reference to the volume now before us. For 
whatever we may think of certain of Dr. Smith’s theories there cannot be a 
doubt that ill the volume which he has just written there is put together,, 
both from original experience and from very careful compilation, an amount 
of information, which is very large, regarding the relative value of the 
several different forms of food — including air and water — which are used 
by man not only in the civilized but in the uncivilized parts of the world. 
In regard to the several subjects treated upon of course it is not to be ex- 
pected that we shall touch. We may, however, notice one or two points 
which strike us as of interest. In regard to Liebig’s extract of meat, the 
author maintains his former view, and expresses a very decided opinion 
“Popular Lectures on Scientific Subjects,” by H. Helmholtz, Professor 
of Physics in the University of Berlin. Translated by E. Atkinson, Ph.D.,. 
F.C.S., Professor of Experimental Science, Staff. College, with an Intro- 
duction by Professor Tyndall. London : Longmans, 1873. 
t “ Foods,” by Edward Smith, M.D., F.R.S. , Inspector for Poor Law pur- 
poses of the Local Government Board. II. King and Co., London, 1873. 
