804 
rock, brecciated or pulverised, but otherwise untreated, 
and the pride of their makers lies in the production of 
monolithic blocks of more uniform texture and more 
free from cracks than can be obtained from ordinary 
quarries. Mr. Watson (p. 76) gives an impressive 
account of the hollow blocks of reinforced concrete, each 
weighing 2464 tons, and measuring 66 by 53 by 50 feet, 
used in harbour-construction at Valparaiso in 1917. 
It seems as if a house of considerable size, with stair- 
cases and passage-ways, could now be moulded round 
a light steel framework as a single piece, and trans- 
ported by flotation to any quarter of the globe. 
The author shows (p. 94) how well-known building- 
stones, with their pleasing colours, are already success- 
fully imitated, and how a great field lies open before 
the manufacturer of light roofing-tiles that may 
compete in our towns with the monotonous grey tints 
of slate. Nothing is likely to oust polished granite 
from its supreme place as a decorative stone for towns ; 
but those who would decry the use of artificial stone 
must remember that the glories of Verona, the Hansa 
Towns, and Hampton Court are largely due to the 
manipulation and moulding of detrital clay. Mr. 
Watson gives a long and interesting history of the 
Portland cement industry, which his specimens fully 
illustrate. He directs attention (pp. 101 and 114) to 
the good acoustic properties of selenitic cement for 
lining walls; but we cannot find a mention of the 
remarkable cement now formed from magnesite and 
used for floors. The early use of the Italian poszolana 
(which even the “ Encyclopedia Britannica” spells 
in places pozsuolana) is well mentioned ; but we doubt 
if (p. 2) Puteoli was also known to the Romans as 
“ Putevolano.” Gy Ass Juste: 
Special Steels: a Concise Treatise on the Constitution, 
' Manufacture, Working, Heat Treatment, and Applica- 
tions of Alloy Steels, for Students, Operators, and Users 
of Special Steels. Chiefly founded on the Researches 
regarding Alloy Steels of Sir Robert Hadfield. By 
Thos. H. Burnham. (Pitman’s Technical Primers 
Series.) Pp. xxii+194. (London: Sir Isaac Pitman 
and Sons, Ltd., 1923.) 5s. net. 
Tus small volume is a welcome addition to the 
literature dealing with special steels, as it contains a 
large amount of useful information compressed into a 
small compass. The necessity for economy in the 
use of iron ore is clearly indicated both by Sir Robert 
A. Hadfield and the author, who show that, by the use 
of special steels, the amount of iron necessary for most 
purposes is greatly reduced. 
Considerable information is given relating to the 
constitution and manufacture of special steels and to 
their later heat or other treatment. Much useful work 
has been done during the past twenty years in connexion 
with the heat treatment of ordinary carbon steel, but 
this treatment, in the case of large masses, is always 
unsatisfactory on account of the impossibility of 
bringing about uniform structural changes. If, how- 
ever, carbon steel is alloyed with other elements a 
considerably greater range of mechanical and other 
properties is available. These considerations are dealt 
with in this small book. Accounts are given of various 
classes of special steels, while under ‘“ chromium 
steel” details are given relating to rustless steel, such 
NO. 2798, VOL. IIT] 
NATURE 



[JUNE 16, 1923 
as its composition, mechanical and heat treatment, 
mechanical properties, resistance to corrosion, and its 
applications. A chapter each is devoted to silicon, 
manganese, and tungsten steels, while some details are 
given respecting the manufacture, properties, and uses 
of other types of special steel. The final chapter (xii.) 
points out the general trend of progress, and there are 
four appendices which deal respectively with: (1) 
carbon steels ; (2) a classified list of papers by Sir 
Robert A. Hadfield; (3) a list of symposia of the 
Faraday Society; and (4) the relation between hardness 
number and shock qualities, tensile strength and 
compression strength of various types of steel. 
The book provides the student and the practical 
man with a handy survey of the subject, and should 
find a place in all technical libraries. W.H. M. 
(1) Animal Nutrition: Foods and Feeding. By E. T. 
Halnan. Pp. 52. 2s. net. (2) Farm Costing and 
Accounts. By C. S. Orwin. Pp. 31. 1s. 6d. net. 
(3) Insect Pests and Fungous Diseases of Farm Crops. 
By A. Roebuck. Pp. 55. 2s. net. (4) Poultry 
Keeping on the Farm. By Edward Brown. Pp. 54. 
(London: Benn Bros., Ltd., 1923.) 2s. net. 
Tue four little books under notice belong to the 
“Successful Farming Series,” the purpose of which 
is ‘‘ to raise the standard of British Farming in all its 
branches.” 
Even in this small compass Mr. E. T. Halnan (1) has 
developed the subject of animal nutrition from the 
fundamental scientific facts to the practical deductions 
drawn therefrom. The exposition is lucid, and the 
book should not only interest farmers who have no 
scientific knowledge, but it should also be of real use 
to them in their daily work. 
(2) In “ Farm Costing and Accounts,” by Prof. C. S. 
Orwin, simple methods are given for keeping financial 
accounts suited to the needs of almost any farmer— 
and incidentally sufficient for purposes of reclaiming 
excess income tax—and an outline of the methods of 
keeping the more intricate costing accounts. 
(3) “Insect Pests and Fungous Diseases of Farm 
Crops,” by Mr. A. Roebuck, contains descriptions of 
the common insect pests and the appearances of plants 
attacked by them or by various fungi. The writer sug- 
gests prophylactic measures such as balanced manures, 
and the avoidance of harbouring places for pests such as 
are found on untidy and ill-kept farms and buildings. 
(4) In “ Poultry Keeping on the Farm,” Mr. Edward 
Brown emphasises the possibility of increasing very 
greatly the number of poultry kept in this country. 
In his opinion this increase can take place most profit- 
ably on farms, where the birds could find much of their 
food ; but he maintains that there are also big open- 
ings for specialised poultry keeping, more especially 
in the vicinity of large towns, and for selective 
breeding. 
The Elementary Principles of Lighting and Photometry. 
By J. W. T. Walsh. Pp. xvi+220. (London: 
Metiven and Co., Ltd., 1923.) 10s, 6d. net. 
Mr. Watsu’s book may be regarded as a useful supple- ; 
ment to pre-War works on illumination. The text may 
be conveniently divided into four main sections. We 
have first an account of the effect of light on the eye, 

