155 
assayers, although sometimes neglected by them. 
Sampling operations being common ground, and 
by no means peculiar to the treatment of the ores 
or alloys of any one particular metal, all refer- 
ence to them is frequently omitted, both in works 
on metallurgy and in text-books on assaying. 
There is also a chapter on the laboratory work 
in a cyanide mill, and a short but adequate 
account of ore and bullion valuation and sale. 
The book compares favourably with its fore- 
runners, both in respect of completeness and 
accuracy of statement, and the patient care dis- 
played by Mr. Smith in collecting and arranging 
all the available data might well be envied by his 
colleagues. There are few changes which can be 
suggested as desirable in the next edition. It 
would perhaps be of interest to add to the his- 
torical section something as to the evolution of 
the assay furnaces, balances, and implements 
generally, say, from the fifteenth century on- 
wards. Another more important addition would 
be some further discussion on the effects of borax 
when mixed with a crucible charge. According 
to many assayers, this influence is always malign, 
giving low results. Mr. Smith is not precise in 
his directions as to the proportion of borax to be 
reserved for acover to the charge in various cases. 
There is also more to be said as to cupel 
absorption and the use of proofs or checks. 
Bullion assayers have long recognised that the 
determination of the absorption of gold and silver 
by a particular brand or batch of cupels is not 
enough, and that the variations in the tempera- 
ture, amount of draught, etc., appreciably affect 
the loss. Accordingly, they use check assays for 
every determination. Ore assayers are often too 
easily satisfied on this head, or in the alternative 
subject themselves unnecessarily to the inconveni- 
ent course of fusing the cupels. If cupel loss were 
determined by the use of checks for each cupella- 
tion or batch of assays, the ex.ca work would, in 
the opinion of the reviewer, be more than repaid 
by the increase of accuracy. In any case, the 
matter should be faced and fully discussed. 
Lastly, exception may be taken to the statement 
on p. 201 that it is necessary to remove the cupels 
immediately after the button has brightened 
(what exactly does Mr. Smith mean by “bright- 
ened’’?). Experience generally, and especially 
the work of Mr. Wilkes (J. Chem. Met. and 
Min.- Soc., 1905, vol. v.,.p. 237) is not in favour 
of this. contention. 
There: is, however, little to criticise in this 
handsome volume. It may safely be placed in 
the hands of students, and will be of the greatest 
value to assayers as a book of reference. 
Teka 
NO; 2320, VOL: 93, 
NATURE 
[APRIL 16, 1914 
SEISMOLOGICAL PHYSICS. 
Modern Seismology. By G. W. Walker, F.R.S. 
Pp. xii+88+10 plates. (London: Longmans, 
Green) and) 'Co., 19%g5) = Price ss.) nec. 
HE first thing to strike one, on glancing 
through this book, is the absence of an 
index; the second is the absence of footnote 
references; and the third is an introduction which, 
purporting to be a history of the progress of 
modern seismology, contains about as many 
errors, of misstatement and omission, as can be 
crowded into five pages of print. But, once the 
book proper is begun, these unfavourable impres- 
sions disappear, and we find an excellent intro- 
duction to the study of that modern seismology 
which is very remote from earthquakes. 
The author’s qualification to deal with the sue 
ject is said to be his experience in having set up at 
Eskdale Muir, and for a short time taken charge 
of, a set of modern seismographs of various types, 
and the book exhibits at once the drawbacks 
and the advantages of this limited justification. 
On one hand, the author’s acquaintance with the 
literature of the subject is evidently limited; for 
instance, he makes several references to Lord 
Rayleigh’s investigation of surface waves in 
solids, but ignores Prof. Lamb’s later and more 
apposite work, and in more purely seismological 
work the reader might well leave the book with 
the entirely erroneous impression that only three 
names—Wiechert, Z6ppritz, and Galitzin—count 
as really important, and that their importance is 
in the order of mention. On the other hand, the 
recentness and brevity of the author’s acquaint- 
ance with the subject leaves him in close touch 
with the difficulties and doubts which beset the 
beginner, and, being a practised observer in other 
branches of physics, and writing from a first-hand 
and current experience, he has produced a lucid 
and sufficient introduction to the subject. 
Beginning with the general dynamical theory 
and principles of construction of modern seismo- 
graphs, which is a clearly put, concise, but withal 
sufficient, account of the subject, he goes on to 
deal with the character of wave motion recorded 
by them and the interpretation of seismograms, 
traversing practically the whole of the ground 
covered by what is known as the modern seismo- 
logy, and forming an excellent introduction to 
that branch of the science. The book deserves, 
and will doubtless run to, a second edition, when 
the author will be able to revise the references 
to earlier work on earthquakes proper, which are 
almost uniformly erroneous in the present issue. 
In spite of this it may confidently be recom- 
mended, not merely to those who approach the 
