Avcust 28, 1902 | 
the length of the spring without having its terminal 
portion shaped after one of Phillips’s curves. On p. 240 
_it is concluded that, provided the windings are numerous 
enough, there are in each turn two points diametrically 
opposite, the attachment of which to the balance would 
procure isochronism. The paper contains also references 
to some experiments, and certain mathematical functions 
are tabulated. The memoir is one which only an expert 
elastician can follow, while an unprejudiced technical ex- 
pert could alone judge of its practical value. This implies 
a combination doubtfully existent in England. 
The book as a whole is full of ideas, and contains in 
addition many valuable facts. It is well worth the 
attention of horologists, whether practical or theoretical. 
In some of the papers, howe~sr, there are indications of 
a little haste, or of careless proof-reading. M. de Vanssay’s 
description of the Kew watch trials seems to be founded 
on a set of regulations superseded in 1890. He specifies 
different rejection limits as applying to ordinary class A 
watches and to those obtaining the distinction “‘ especially 
good.” This is not now the case, the distinction denoting 
simply the attainment of at least 80 per cent. of the total 
possible marks. In some of M. Faddegon’s mathematical 
expressions there are a few rather obvious misprints, and 
the paging is wrong in the few cross-references in the 
text of his paper. 
In M. Féry’s description of a pendulum with electric 
“restitution” the letters employed in the text are 
omitted in Figs. 1 and 2 on p. 70, rendering the descrip- 
tion difficult to follow. 
errata in intermediate steps in M. Caspari’s memoir. 
Thus on p. 234 the sign of equation (7) is wrong, and 
the term containing 4 in the line above is also given in- 
correctly. The suffix ina, is omitted somewhat arbitrarily 
on pp. 239 and 244, and on the latter page its factor 
sin @ is omitted several times. The errata, however, 
are seldom of a kind likely to cause serious trouble. 
C. C. 
TRADES’ WASTE AND RIVER POLLUTION. 
Trades Waste: its Treatment and Utilisation. By W. 
Naylor. (London : Charles Griffin and Co., Ltd., 1902.) 
E this volume the author, who is the chief inspector of 
rivers of the Ribble Joint Committee and consulting 
engineer on sanitation and rivers’ pollution to the Somer- 
set County Council and other public bodies, has put 
together the results of his experience and observation, 
as to the causes of the pollution of rivers and as to 
the best known practical means of preventing it. The 
subject, it need hardly be said, is of the greatest import- 
ance, but it is also one of ever-increasing difficulty and 
perplexity. It has been forced upon public attention with 
more or less insistence at irregular intervals during the Jast 
half century. In 1867 the whole question was relegated 
toa Royal Commission, the reports of which are justly 
styled by the author as by far the best production on the 
subject hitherto published in any country. The labours 
of this Commission paved the way for the Rivers’ Pollution 
Act of 1876, but this, as administered by the various 
local sanitary authorities, proved to be of little practical 
good. There can be no question that if it had been 
NO. 1713, VOL. 66] 
NATURE 
There are a good many slight | 
413 
efficiently administered much might have been accom- 
plished, and by simple means, and we should not have had 
to wait for the more costly operations which have resulted 
from the Local Government Act of 1888. Had the local 
authorities put the Act in operation with the vigour which 
they showed in the case of the Alkali Works Regulation 
Act a great public benefit might have been effected with 
comparatively little friction or irksomeness. The author 
points out how the opportunity was allowed to slip. 
‘*Land on which to instal plant might have been 
obtained which cannot now be procured, and machinery 
might have been put down, and drains laid at levels which 
would have permitted the interception of the drainage 
without the resort to pumping now in many cases neces- 
sary. But this was notdone. Manufacturers are just as 
much to blame themselves as anybody. In many cases 
it was due to their opposition as large ratepayers or 
to their personal influence on the local governing autho- 
rities, that the Act remained a dead-letter.” 
Whether the larger powers vested in such bodies as the 
two boards of the Mersey and Irwell Joint Committee 
and the Ribble Joint Committee, some of which have also 
been acquired,or sought to be acquired,by county councils, 
will result in a larger measure of good remains to be 
seen. But it is evident from the manner in which various 
trade associations, as, for example, the Paper Makers’ 
Association, have been moved that a more stringent 
administration of the Act throughout the country is in 
contemplation, and that the opposition, overt or covert, 
of many of the manufacturers has still to be reckoned 
with, 
In a chapter on chemical engineering the author deals 
with the general principles underlying the treatment of 
trades’ waste, either as liquid or semi-solid products. He 
discusses the “laws” regulating the subsidence of solid 
particles floating in liquids, the conditions determining 
their aggregation and the various modes in which pre- 
cipitants are manufactured. He then gives typical illus- 
trations of the application of these principles as carried 
out in actual practice, as in the Mather and Platt system 
and in the continental tank systems. He gives details of 
the mode of construction of precipitation tanks, together 
with a design of retaining walls for resisting hydraulic 
pressures, &c. This chapter is illustrated by diagrams 
and plans, together with a number of well-executed 
“process” reproductions of photographs of installations 
in actual use. It is not, however, very obvious why it 
should be headed “Chemical Engineering,” since it is 
mainly concerned with the application of physical and 
mechanical principles to the filtration and clarification 
of more or less turbid liquids. 
The remaining chapters, seven in number, deal with 
some of the special industries which produce waste in 
notable amounts, such as woollen mills, tanneries and fell- 
mongeries, breweries and distilleries, bleach and dye 
works, calico printing works, paper making and chemical 
works. As a matter of fact, however, the author treats 
only comparatively few of the waste-producing industries. 
The various industries, adopting the classification of 
the Society of Chemical Industry, may be grouped into 
twenty-two classes. According to the author, only five 
of these may be said to have no liquid waste of con- 
sequence as regards volume, whereas the remaining 
