JuLy 31, 1902] 
NATURE 315 
which, as now described, is in line with previous know- 
ledge and most recent investigation. The figure in the 
first volume which it is to replace, incomprehensible as 
it stands, is now admitted by the author to have been 
due to confusion, in the attempt to reconstruct his own 
rough drawings during the intervals of military duty. If 
only for this we forgive him, despite his somewhat 
emphatic contentment with the original, now condemned. 
An attractive elegance is a leading feature of this 
book, and by this it is calculated to draw the reader to 
its subject. In this respect it contrasts both forcibly and 
favourably with the baldness of expression and lack 
of culture which characterise many of its would-be 
competitors. 
THE CLASSICS OF PHYSICAL SCIENCE. 
Scientific Memoirs. Edited by J. S. Ames, Ph.D. 
Fifteen volumes, prices varying from .60 to 1.00 dollar. 
each. (New York: American Book Company, 1898 
to 1902.) 
T is refreshing to meet with this series. Not that 
the contents are novel, though recent things are not 
lacking. It is the aim of the series which is stimulating. 
Our students are gradually being degraded into a reliance 
upon text-books for nourishment instead of being 
brought up on a study of scientific classics. It was not 
ever thus. Time was when text-books were almost 
unknown, and knowledge of science had to be acquired 
by a study of original sources. The more modern craze 
for, and reliance upon, examinational tests has altered all 
that. Nowadays a man must knowa little bit of every 
branch of the rapidly extending circle of sciences in 
order to take a county scholarship or a degree. And 
text-books spring up by the dozen to supply the very 
special wants of any newly created examination. It is 
possible, and it is to be hoped, that the new regulations 
in the University of London will tend to remedy this 
state of affairs. Much greater stress is to be laid upon 
a knowledge of recently published work, and the habit of 
mind that is so induced is bound to bea healthy one. 
We wish, too, that for the less recent work men were 
more encouraged to put text-books on one side and study 
some one branch at least in the original memoirs. 
This. handy series in fifteen volumes is a move in the 
right direction, It consists of translations or reprints 
{in English) of memoirs dating from the rise of physical 
science to the present day. Each volume is confined to 
one subject, has a separate editor, who writes a very 
short preface—in part historical, in part elucidatory— 
and also a brief biographical sketch of each of the 
writers whose memoirs are selected from. The first 
volume consists of papers by Gay-Lussac, Joule, and 
Wm. Thomson and Joule on the “Free Expansion of 
Gases.” In the brief introductory sketch it might have 
been well if the editor had pointed out the essential 
distinction between the earlier and the later experiments. 
Thus, while the absence of a fall of temperature in Gay- 
Lussac’s experiments is so far a proof of Mayer’s hypo- 
thesis, its absence in Joule and Thomson’s experiments 
would not have proved it. In fact, the editor is labour- 
ing under a very common mistake in thinking that the 
NO. 1709, VOL. 66] 
experiments all satisfy the condition of zero performance 
of external work ; this is the case in the first but not in 
the last. It is a pity that the expression “free expan- 
sion” is not reserved for cases which satisfy the above 
condition, and some other term (e.g. throttle expansion— 
the term of the refrigerating engineer) be employed 
where the conditions are those which obtain in porous 
plug experiments or the “ wire drawing” of steam. 
The other volumes are as follows :— 
Vol. ii. “Prismatic and Diffraction Spectra.” Papers 
by Fraunhofer and Wollaston. 
Vol. ili. “ Rontgen Rays.” The now historical papers 
of Rontgen and Stokes (the Wilde Lecture) and J. J. 
Thomson. 
Vol. iv. “ The Modern Theory of Solutions.” Pfeffer, 
van ’t Hoff, Arrhenius and Raoult. 
Vol. v. “The Laws of Gases.” 
Amagat. 
Vol. vi. “The Second Law of Thermodynamics.’ 
Carnot, Clausius and Thomson. ; 
Vol. vii. “The Fundamental Laws of Electrolytic 
Conduction.” Faraday, Hittorf and Kohlrausch. 
Vol. viii. “The Effects of a Magnetic Field on Radia- 
tion.” Faraday, Kerr and Zeeman. 
Is it a fact, as stated by the editor, that in the Hall 
effect “the stream lines of an electric current flowing 
through a thin conducting sheet transverse to a magnetic 
field are deflected”? That the lines of electric force are 
deflected is, of course, certain ; but the two statements 
are not equivalent. 
Vol. ix. ““‘The Laws of Gravitation.” 
Bouguer, Cavendish, with abstracts from others. 
Vol. x. “The Wave Theory of Light.” Huygens, 
Young and Fresnel. 
Vols. xi. and xii. “The Discovery of Induced Electric 
Currents.” Joseph Henry and Faraday. 
Vol. xiii. “The Foundations of Stereo-chemistry.” 
Pasteur, van ’t Hoff, Le Bel and Wislicenus. 
Vol. xiv. ‘‘The Expansion of Gases by Heat.” 
Dalton, Gay-Lussac, Regnault and Chappuis. 
Vol. xv. “The Laws of Radiation and Absorption.” 
Prévost, Stewart, Kirchhoff, and Kirchhoff and Bunsen. 
The editor attributes to Kirchhoff the first rigorous 
proofs of the celebrated law connecting emission and 
absorption. This is the common view; but in the light 
of Rayleigh’s recent vindication of Stewart in the PAz/o- 
sophical Magazine this attribution is inadmissible. 
It will be seen from the above very brief summary 
what the kind of selection has been. Other editors 
might very well have selected differently without effect- 
ing any improvement. 
If a criticism may be attempted, it is that objection 
may be easily raised to the abridgment which several 
of the papers have undergone. Much may, of course, be 
urged in favour of this pruning when carefully done ; 
but the necessity for it is certainly to be regretted. It 
recalls the similar process which novels have been obliged 
to submit to—a process which suggested to Puach the 
brilliant idea of republishing pictures with parts deleted 
The editors carefully point out, however, when they have 
applied the knife, and they appear to have used it with 
care. 
At the end of each volume is a bibliography, in which 
reference to allied papers is made. 
With this our task is done. This is not the time to 
discuss the matter of the papers themselves. Let it only 
Robert Boyle and 
Newton, 
