The Sun.
London, England, 1844-06-29 00:00:00

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THE ATMOSPHEM uIC RAILWAk - - ",----,/-"\
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The principle of atmospheric propulsion for r
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has lately assumed a degree of importance w :.4.t.1''..,:',%(-4.-:I3P--.-1". ,--
previous aspect rendered it (Nit little likely to iiitagnic.- -..Et.l.t'-',1")
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Few subjects of practical scie. nee have given •W 1 •-•;';3[1.1%
greater diversity of opinion than this, and three C•lrs.`.24:''..-- -1--R)!,/
professional reports upon it have lately been 11144..jtL1- '''''
The first, by M. Mallet for the V.rench Govern mg* tit riVcTSM ;jr
has proved to be so imperfect in the experiments,
and so erroneous in the statements,. that although
highly laudatory of the invention, it appears to be
by common consent consigned to oblivion. A report of
a very different kind has lately been made by Mr. Ro-
bert Stephenson, and from his great experience and high
character as an engineer, his deliberate and well-consi-
dered opinion on such a subject cannot fail to carry with
it great weight. The report in question was .made to
the Directors of the proposed Chester and Holy head
Railway, and a short abstract of it will be interest.;ng to
those whose limited knowledge of the subject may not
enable them to follow the author through all his detads.
After a brief description of the apparatus, Mr. Ro-
bert Stephenson proceeds to detail the experiments ha
instituted to test its powers on the Dublin and Dalkey
Railway. The apparatus consists of a pipe, 15 inches
diameter, extendng the entire length of the railway ;
and along this pipe a piston passes, to which the car-
riages are attached, which moves along with them, the
motion being communicated to the piston by atmospheric
pressure, when the air is partially exhausted from the
pipe by a powerful pump fixed at one end of the main.
A portion only of the air can be thus exhausted from
the pipe before the train starts ; and the remainder of the
air is then pumped out as the train moves forward, the
velocity of the train being exactly equal to the rate at
which the air remaining. :in the tube is; withdrawn by the
pump. The leakage of air into the partially-exhausted
tube is found to be remarkably uniform at all degrees
of exhaustion, the ,barometer guage falling about one
inch per minute, vi en the action of the pump is
stopped. As the pump, however, can only extract a
given volume of air in a certain time, it follows that
for every cubic foot of air leaßing• into the pipe when
the exhaustion is equal to 15 inch eh of mercury, two
cubic feet must be extracted by the vlump in conse-
quence of the expansion of the air in th, a partially ex-
hausted pipe. This is one of the great fundamental
difficulties ; and Mr. Stephenson then goes into some
calculations based upon experiments, showing" a loss of
power from this and other causes varying from (39 to 71
per cent. on the theoretical velocity. About 30 peC cent.
of this loss arises from the leakage already described; and
about 41 per cent. is ascribed principally to the leakage
at the piston, which is obliged to be about one inch less
in diameter than the pipe; the aperture though covered
by an expanding cup of leather, necessarily permitting
a large quantity of air to pass in during the rapid 'no-
tion .of the piston along the pipe. Mr. Stephenson next
slums the actual power expended in moving trains of
different weights and at various velocities ; and by'
calculating the power expended in producing the
partial vacuum :in the pipe before the train begins to
move, and the subsequent power employed while the
train is in motion, it appears that on the line at Dalkey,
which is 11 mile long, the lightest train, weiOling 25i
tons, travelling at the rate of 341 miles per hour, con-
sumed a power equal to 322 horses ; and the powm for
other trains varied with the weight and velocity, a !grain
of 58 tons with a velocity of 20r miles per hour, requir-
ing a power equal to 506 horses. This enormous power
3,17. Stephenson divides under various heads, showing:
1 the separate amounts consumed in producing the•
vacuum, in working the train, in the atmospheric
resistance, and in the friction on the rails. A compa•
rison is then made on the expenditure of power for
working the incline on the Birmingham Railway at
Camden-town ; from which it appears that while the
loss by the atmospheric system is 74 per cent., that on
the Camden incline (worked by a rope and a fixed en-
gine) is only 45 per cent. Calculations are then made,
on the cost of construction and the expense of working
a railway by locomotive engines and by the atmospheric
system. The extra cost of construction for the atmo-
spheric system Mr. Stephenson estimates at 11,0001. per
mile ; from which in certain cases some deduction may
be made for using increased gradients, and also a saving
by dispensing with the outlay required for locomotive
engines.

11r. Stephenson's report is based on mere matters or
fact; and considering the occasion of his report, he has
very wisely abstained from entering into any abstract
theoretical questions. A very able mathematical in-
vestigation of several points connected with this
report has, however, been made by Mr. Hera-
path, which has been published in the last
two numbers of Herapath s Railway Journal. In
this investigation Mr. Herapath has developed by
mathematical analysis some most important and in-
teresting points, which clear up the apparent anoma-
lies in the experiments published by :Mr. Stephen-
son ; and he has deduced by an investigation, which
agrees completely in its results with the experiments in
question, that one great source of the immense loss
of power observed in the working of the atmospheric
railway arises from the friction of the air in the
main, which produces a constantly varying density from
one end of the pipe to the other, and causes a loss of Ili
miles per hour for each mile that the length of the tube
extends. The loss of velocity by this cause only would
therefore, in a main four miles long, be 45 miles per
hour from the theoretical velocity, even if no leakage at
all occurred, leaving about 10 miles an hour as the re-
sulting velocity which could be obtained at the com-
mencement of each of the mains of four miles long.
Fewer experiments have been made on the motions of
air than on almost any other branch of science connected
with engineering ; but Mr. Herapath has quoted from a
work of high repute two experiments of a very exten-
sive character, which are nearly analogous to the subject
under consideration, and they both failed from the same
cause that he has pointed out as exerting so great an
influence in the atmospheric railway.
Professor Barlow and Sir Frederick Smith some time
since also made a report to the President of the Board
of Trade on the atmospheric railways, in which, although
they experimented with a much less perfect apparatus,
their conclusions agree well with the facts more
recently developed. They arrived at the same
conclusion as to the great loss of power. In
Mr. Stephenson's experiments the power of the engine
is calculated at the usual amount of 33,0001 b. raised
one foot high as the unit of a horse's power. The state•
inents made by the advocates of the atmospheric system
have all shown an expenditure of power enormously be-
low these amounts stated by Mr. Stephenson ; and it
was not until the recent examination of witnesses in
the Committee of the House of Commons on the subject
of this invention, that it was elicited from them that
all the calculations of the horse's power were made
by using 66,0001 b. as the unit, thus reducing the
power nominally to one-half its real amount. That a
mode of calculation so totally different from anything that
had ever been used before should have been thus adopted
without the fact being so stated, when the object could
merely be to exhibit the invention in a more favourable
light than it would otherwise appear in, is calculated to
throw a strong suspicion over the other statements made
by the same parties ; and, indeed, these experiments of
Ur. Stephenson have clearly shown that many of the
statements which have been made in favour of the in-
vention are not to be relied on, and are at variance with
the facts in some most important particulars.
Were the difficulties which attend this invention purely
mechanical, they would be comparatively unimportant ;
for such is the state of mechanical science at the
present day, that nothing seems impossible for it to
accomplish. But this invention appears to have far
greater difficulties to contend with ; for, unless the
experiments and deductions of some of the most
scientific and practical men of the day are erroneous,
the laws of nature are against its success, and those
who are urging upon so impoverished a company as that
of the Croydon Railway such an enormously expensive
experiment, are incurring a responsibility of no ordinary
character. It should also be observed, that Sir James
M`lSTeil has within these few days made a report on the
Atmospheric Railway, in which he arrives at exactly the
same conclusion as Mr. Robert Stephenson, of its inappli-
cability to the ordinary purposes of railway communica-
tion.— Times.

THE SWORD FISH.—Mr. Fleming, one of the
owners of the Royal Archer of Glasgow, has left at our
office, for a few hours, for the inspection of the curious,
a piece of the timber belonging to that vessel, with the
horn or sword of a sword fish sticking in it to the ex-
traordinary depth of 14 inches. This monster of the
deep seems to have come in contact with the Royal
Archer, on its homeward voyage from Ichaboe, and
struck the bow of the vessel with such extraordinary
violence, as to force its weapon through two plates of
copper and upwards of a foot into the timber, where it
was broken off, either by the' violence of the shock, or
the desperate efforts of the fish to recover its liberty.
It was most fortunate that the weapon remained in the
bow of the vessel, for it had made an opening, which, if
not plugged up in that manner, would probably have
sunk it.—Liverpool Tunes.
THE WEATHER IN DERBYSHIRE.—We have at last
been favoured with a fall of rain, which has already
worked a wonderful alteration on the face of nature.
The hay harvest in this neighbourhood may be said to
be at a stand still, as most parties are anxious to reap
the benefit of the present rain, but we are afraid in
many instances the grass had been so thoroughly burnt
up that it will never recover. On the other hand the
wheat, oat, barley, bean, and potato crops are evidently
receiving immense benefit from the rain ; and although
in many cases they are irreparably injured, in others
there is great promise of abundance.—Derby Mercury.
[ADVERTISEMENT.j—A DISEASED STOMACH.—•"
CURE EXTRAORDINARY BY HOLLOWAY'S PILLS.—Mrs.
Aikins, widow of the late Captain Aikins, residing at
Connaught-terrace, Edgeware-road. This lady bad
been in India, where her liver and stomach became dis-
eased, so much so that she could scarcely keep the
slightest food on her stomach. She was very weak and
debilitated, and suffered continually from sick headache,
a nervousness, and lowness of spirits. In six weeks,
however wonderful it may appear, she was restored to a
high state of health by this unrivalled medicine, which is
a certain remedy in all liver, bilious, and stomach corn-
plaints.—Sold (also Holloway's Ointment) at Professor
Holloway's Establishment, 244, Strand (where advice
may be had gratis), and by almost all respectable Ven-
dors of Medicine throughout the civilised world.
MONTROSE.—We have the satisfaction to state, that
Lord Panmure, with his characteristic benevolence, has
been pleased to transmit the munificent donation of 1001.
for the benefit of the Montrose Lunatic Asylum, &c.,
inclosed in the following letter to the Secretary :
" Brechin Castle, June 19, 1844.
" Dear Sir,—The state of my health at present pre-
vents me attending the meeting of the Managers of the
Montrose Royal Lunatic Asylum, &e., to-morrow ; but
I beg leave to inclose a small donation, for the benifit of
that useful and valuable institution.— I am, dear Sir,
yours faithfully, " PANMURE.
" To James Leighton, Esq."