APRIL 4, 1912] 
be advantageous. Dr. Fottinger’s system of hydraulic 
transmission gives an efficiency of about go per cent. 
at full speed. Both electrical and hydraulic systems 
admit of very large powers astern without separate 
prime movers. Helical gears with machine-cut teeth 
(made by Messrs. Parsons) were fitted to the steamers 
forming the subject of the paper. The loss in this 
gearing amounts to 1°5 per cent. only. There is 
practically no noise; a slight whistling sound can be 
heard by listening carefully when in the passenger 
uarters. There are no vibrations or trepidations. 
ir Charles Parsons stated that most of the 1°5 per 
cent. waste occurred in the pinion bearings. There 
is no wear in the teeth, the oil film apparently being 
preserved unbroken. Dr. Féttinger raised the point 
of the limit of power which could be transmitted ; 
his hydraulic gear was being fitted for very large 
powers. Mechanical gearing has been used for com- 
paratively low powers up to the present, but no doubt 
can be developed to a much greater extent. 
The discussion of the previous day on Mr. W. I. 
Knudson’s paper on the Selandia provoked further 
comments on the Diesel engine from speakers in the 
discussion on Prof Bile’s paper. The height of 
Diesel engines for a warship would be much greater 
than that of geared turbines; with the oil engines 
the most vulnerable parts of the machinery might be 
above the water line. The Selandia was reported at 
the meeting to be making good progress on her first 
voyage, and was passing through the Red Sea at 
above eleven knots. 
In all seventeen papers were read and discussed 
at the meeting; the limitations of space have for- 
bidden reference being made here to other than the 
more important papers. 
THE INTERNATIONAL SMOKE ABATE- 
MENT EXHIBITION. 
aie remarkably clear atmosphere which has been 
observed in many industrial centres during the 
coal strike has afforded an excellent object-lesson in 
smoke abatement. It should emphasise the desir- 
ability of making these conditions permanent. That 
the removal of smoke comes well within the range 
of practical achievement has been amply demonstrated 
by the International Smoke Abatement Exhibition 
which has just been held under the auspices of the 
London Coal Smoke Abatement Society. In the 
official catalogue of the exhibition we find references 
not only to the exhibits of smoke-saving and smoke- 
preventing appliances, but to practical demonstrations 
of their use. The exhibition has further provided 
opportunity for a series of excellent lectures and 
addresses by well-known authorities, which include 
men of science, engineers, and manufacturers of 
English, German, and American nationality. 
The exhibits may be divided into two categories, 
those which are devised for burning coal or partially 
coked material smokelessly, and those which replace 
the solid fuel by oil, gas, or electricity. 
Anyone who may have watched the cookery demon- 
strations with gas cookers or observed the great im- 
provement in the appearance of the various gas fires, 
or examined the electrical heating apparatus for domes- 
tic use, must have been impressed with the great ad- 
vantage in cleanliness, convenience, and efficiency which 
these methods of heating possess over the coal fire. 
Indeed, it is impossible not to carry away the con- 
viction that in the use of gas and electricity for heat- 
ing and cooking, lies our future hope of salvation 
from the smoke fiend. The chief obstacle at present 
is their cost. Yet in spite of the high price of gas 
as compared with coal of the same calorific value, it 
NO. 2214, VOL. 89] 
NATURE 
125 
is interesting to learn that during the last ten years 
there has been an increase of nearly two million gas 
cookers in the United Kingdom, whilst the total 
number of gas heating and cooking appliances in- 
stalled by the London gas companies in 1910 reached 
1,300,000. 
This is a matter of considerable importance when 
it is remembered that the domestic hearth not only 
turns out by far the greater proportion of soot on 
: the coal burnt, but soot of that particularly obnoxious 
quality which, by its high content of tar, is the most 
adhesive and permanent. 
We have not space to refer to the numerous papers 
read at the conference, but must refer our readers 
to the small volume which has been issued by the 
Coal Smoke Abatement Society, 25 Victoria Street, 
Westminster, price 2s. 6d., which is well worth 
perusal by those who are interested in the. various 
phases of the smoke question. 
The papers may be divided into those dealing 
with (x) the causes, (2) the cure, and (3) 
the effects of smoke. Among the last, valuable in- 
formation was contributed by Sir A. Church and Mr. 
N. Heaton on the important subject of the disintegra- 
tion of building stone and the destruction of mural 
decoration by atmospheric sulphuric acid arising from 
burning coal, and experimental evidence showed that 
the stonework of ancient historic buildings was being 
slowly corroded. Dr. Rideal, who dealt with the 
effects on metal work, found that the rust on a roof 
girder of Charing Cross Station which collapsed in 
1g05 contained 4°25 per cent. of sulphuric acid, equal 
to nearly 9 per cent. of ferrous sulphate. The effects 
on vegetation are even more disastrous, and striking 
experimental results were recorded by Mr. W. J. 
Bean, assistant curator of Kew Gardens, and Mr. 
A. G. Ruston, of the Agricultural Department of 
the University of Leeds. The effects on health were 
discussed by Mr. W. B. Smith, chairman of the Air 
Purification Committee of the Glasgow Corporation, 
who gave statistics proving the high mortality from 
bronchial diseases during town fogs. 
Though there has been some repetition of old argu- 
ments, opinions, and facts, these are subjects which 
cannot be too frequently dinned into the ears of an 
indifferent public in the hope that an echo of them 
may ultimately reach the local authorities and rouse 
them to a‘sense of their duty. 
It is satisfactory, however, to learn from Mr. Lemp- 
fert, of the Meteorological Office, and Mr. J. B. C. 
Kershaw that matters are slowly improving. The 
number of hours of bright sunshine in the year in 
industrial centres, compared with certain country 
places, has steadily increased, showing that either the 
country stations are making more smoke or the 
towns less. The author of the paper, Mr. Lempfert, 
takes the latter and more sanguine view. He makes 
the significant remark that “the great difference 
between the figures for winter and those for summer 
suggests that domestic smoke rather than factory 
smoke is mainly responsible for the loss of sunshine.” 
Now legislation in this country has not yet ventured 
to invade the sanctity of the domestic hearth, yet it 
is proved beyond question that it is the worst offender. 
Mr. Nicholson, smoke inspector for Sheffield, asks, 
with perfect justification, ‘‘ Why should our domestic 
fireplaces be allowed to create an unnecessary nuisance 
any-more than any other fireplace or furnace?”’ The 
answer is: provide cheap gas and electricity. The 
splendid combined exhibit of the gas companies and 
of the London electric supply and other manufac- 
turers of electric appliances leaves little to be desired 
| in the apparatus designed to utilise these two forms 
| of energy. 
