730 
Gray, Willans and others; but he is himself 
certainly entitled to the thanks of the scientific 
and the practical worker in the field of ther- 
modynamics, pure and applied, for the extent 
to which he has developed his theme, and for 
the excellence of his own work. The informa- 
tion given by Mr. Golding had hitherto been 
scattered through various technical periodicals 
and transactions of learned societies, often 
quite inaccessible to the average practitioner, 
and its collection into a formal and logical 
treatise is a veritable boon to the student of 
heat-engine-efficiencies, whether as_ scholar, 
simply, or as practitioner of the art of engine- 
design and construction. The text is clear 
and well-written, and the profuse illustration 
and excellent engraving throughout the book 
are worthy of all praise. The tables, so far as 
we have checked them by differences, seem ac- 
curate and the diagrams are remarkably well- 
selected as illustrations of the facts and prin- 
ciples involved in the discussion. Boulvin’s 
diagram is introduced as the ‘complete entropy- 
diagram’ and its use is well-explained and 
illustrated. 
The entropy of water and of steam are com- 
puted and tabulated; the standard engine- 
cycles and their details are discussed; the 
effects of jacketing and compounding the 
steam-engine and those of superheating and 
of initial condensation are studied; the con- 
version of indicator to entropy-diagrams is 
shown and the thermodynamics and physics of 
the steam-engines are treated at ample length. 
Similarly complete discussions of the air, gas 
and oil-engines are presented and many novel 
applications of the system are shown. The 
book, as a whole, is an admirable presentation 
of its subject. A valuable feature is a new 
table of the weights of saturated steam per 
cubic foot, for each one-tenth-pound pressure, 
up to 219, with differences computed for 
each one one-hundreth or a pound per square- 
inch. 
Professor Boulvin’s work, as translated by 
Donkin, is that of a master in the new art. Its 
author was one of the first to appreciate and to 
take up the Gibbs’ system of thermodynamic 
discussion and incorporated it into his work on 
the steam-engine, published in 1893. The 
SCIENCE. 
[N. 8S. Von. X. No. 255. 
present work appeared in the Revue de Mécan- 
ique in 1897, and, at the request of Mr. Donkin, 
who offered to make the translation into Eng- 
lish, the author consented to reproduce the dis- 
cussion in book form. It is, as the translator 
says: ‘‘A short syllabus of the principles of 
thermodynawics as applied to heat-engines and 
its chief claim to originality lies in its syste- 
matic method of using temperature-entropy 
diagrams.’’ The author deduces a ‘ heat-bal- 
ance’ from the data of a steam-engine trial, by 
the employment of the theta-phi chart in a very 
simple and direct manner, and avoids the 
lengthy and troublesome computations neces- 
sary in the algebraic system of Hirn. The 
older systems were incomplete ; the present is 
practically perfect in many points in which the 
others were defective. The ‘complete entropy- 
chart’ of Boulvin is especially useful in this 
work. The Boulvin diagrams and chart af- 
ford a means of not only making a heat-balance, 
but also of following the movements of heat 
throughout the cycle, and this without other 
computations than those required in reducing 
to scale the quantities to be dealt with. As 
observed by the translator: ‘‘The best stan- 
dard of efficiency for the steam-engine has been 
much discussed and the question would be 
practically solved if, for every steam-engine, we 
had entropy-diagrams, all traced to the same 
scales of entropy and temperature for a unit- 
weight of steam coming from the boiler. These 
diagrams could be compared with each other, 
and in any country, and the smallest variations 
in the work of each engine graphically shown 
without any explanation being necessary.’’ In 
this publication, Professor Boulvin has added a 
new method of dealing with clearances and 
throttled steam ; ascertaining the action of the 
walls of the cylinder in heat-exchanges, and 
representing it in all cases independently of 
the extent or character of compression. The 
weights and measures employed are in this 
work entirely metric and the student can thus 
find in the last-named two treatises opportunity 
to compare the same methods, employing these 
different symbolic and measuring systems for 
similar purposes. 
The plan of the book is thoroughly syste- 
matic, commencing with a study of the funda- 
