265 
NATURE 
[May 14, 1914 
Diesel or slow-combustion oil 
authors term it. 
The authors, in addition to original 
matter, have brought together into convenient 
form for reference the results of experimental 
work and the information in regard to construc- 
tive details published in the columns of the 
much 
technical Press of the past ten years, or embodied | 
in the numerous papers read before the leading 
engineering societies of the world; for this 
reason alone the book will prove invaluable both 
to the many engineering firms which now build 
these engines, and to the engineers who have 
installed them in power stations, factories, and 
ships. 
The first four chapters deal with the theory of 
the laws of perfect gases, the work which can be 
obtained from a given volume of gas when ex- 
panding under given conditions, and the applica- 
tion of the well-known entropy diagrams to the 
study of the internal combustion engine. The 
next chapter deals with oil fuels suitable for these 
engines, their physical properties and methods of 
transport, and storage; in this connection the 
authors refer to the vast shale deposits in Australia, 
and to their utilisation for the production of oils for 
power purposes in that continent. In connection 
with the question of the cost of power generated 
by Diesel engines, it may be mentioned that in a 
test of a 200 b.h.p. two-cylinder four-stroke cycle 
engine, Mr. Eberle obtained under full load a 
thermal efficiency of 34°2 per cent. reckoned on 
the b.h.p., a wonderfully good result. In connec- 
tion with the testing of Diesel engines the authors 
give some useful advice as to the care and atten- 
tion necessary in order to maintain a high state 
of efficiency. 
In view of the importance to designers of 
Diesel engines of a thorough knowledge of the 
theory and practice of air compression, the 
authors have wisely devoted a whole chapter to 
this subject, and have done their work admirably. 
The ninth chapter deals with the data and calcula- 
tions needed in the design of cylinders, crank- 
shafts, valves, flywheels, and reversing gears, 
while the concluding chapter is devoted to an 
account, well illustrated, of a number of recently- 
constructed Diesel engines for all classes of land 
and marine work; it is in connection with marine 
work that the greatést advance has taken place 
in the last two or three years. In an appendix 
the authors give a most useful abridgment of 
the principal patents connected with this remark- 
able motor and its developments. 
(4) In this volume, which forms one of a series 
of text-books on the chemistry of the national 
industries, Mr, Searle deals with the three impor- | 
NO: .2324° VOL, 93) 
engine, as_ the 
tant building materials—cements, concrete, and 
bricks. The importance of a knowledge of chem- 
istry in the manufacture of cement has been long 
recognised, and to this fact is due the great 
_ advance this industry has made during the past 
twenty years, but it is only recently that the value 
of chemical research to the brickmaker has been 
fully realised. In the first five chapters the 
author deals with cement, most attention being 
given naturally to Portland cement; he discusses 
fully the necessary properties of the raw mate- 
rials, and the various methods of manufacture; 
Mr. Searle is of opinion that with equal care and 
skill both the older wet process and the modern 
dry process produce good results. The chemical 
and physical changes which occur both in the 
manufacture and in the setting of cements are 
most fully and thoroughly discussed, especially the 
chemical relations between the lime, alumina, and 
silica. In chapter v. the question of the testing 
of cement is taken up, the various methods 
adopted are fully explained, and the importance 
of cement-sand tests is clearly brought out, the 
author expressing his opinion that tensile tests 
of neat cement are largely futile; in dealing with 
the tests for soundness it is shown that this is a 
test which it is difficult to carry out with accuracy, 
and that, as a matter of fact, the majority of the 
Portland cements now on the market will pass all 
the ordinary tests for soundness. 
Two chapters are devoted to the components of 
concrete and its preparation, and much excellent 
practical advice is given; then follows a chapter 
en reinforced concrete; the author points out that 
many of the formule now used in calculation 
work contain constants, which in the hands of the 
experienced man are safely used, but when used 
by a beginner may lead to serious blunders. The 
remainder of the book is devoted to brickmaking ; 
the chemical and physical properties of the raw 
materials are fully discussed, the various pro- 
cesses of manufacture described, and the proper- 
ties of finished bricks of various classes explained. 
Mr. Searle has written a thoroughly sound, valu- 
able text-book, which ought to prove of great 
service to manufacturers, builders, and archi- 
tects. T. Habe 
OUR BOOKSHELF. 
Lehrbuch der Paléozoologie. Teil ii., Wirbeltiere- 
By Dr. E.:F. Stromerivy Reichenbachh eep: 
ix+32. (Leipzig and Berlin: B.‘G. Teubner, 
1912.) Price 10 marks. 
THE second part of Dr. Stromer’s text-book of 
paleozoology deals with the fossil vertebrates in 
the same concise and philosophical manner as his 
previous account of the invertebrates. The 
