The Sun.
London, England, 1845-07-10 00:00:00

LOCOMOTIVE STEAM-ENGI'',;ES

The paper read at the last meeting of the Institution of
Civil Engineers was by Mr. J. G. Bodmer, M. Inst. C. E.,
On the advantages of working engines with high-pressure
steam expansively arid at great velocities." The author based
his observations upon the principle of a considerable area of
piston being essential for taking advantage of the initiative
impulse of highly elastic steam, in contradistinction to the idea
of its percussive action, which had some time ago found advo-
cates. In order, therefore, to take advantage of this action,
and be enabled to cut off the steam at an early period of the
stroke, the piston. at short intervals, and consequently making
a great number of strokes within a given time, must travel over
a limited distance, that as little as possible of the heat, and con-
sequently of the elasticity, should he lost.
It has been generally acknowledged that the action of a short
crank and rapid stroke is very disadvantageous to the framing
..nd foundations of ordinary engines. Mr. Bodmer has, in con-
structing his compensating engines, concentrated the action
and confined the strain to the crank, connecting rod, and piston
rod. By this circumstance, he has been enabled to carry the
expansive principle to such an extent as to deliver the steam
into the condenser almost in a state of mere vapour, or within
three pounds of a vacuum. The saving of fuel must, there-
fore, be in proportion, and must be a very considerable
reduction of the actual weight of the machinery and of the
coals on board steam-vessels on long voyages. The paper
considered at great length the reasonings upon these prin-
ciples, and in tabular forms gave the comparative results of
this and the ordinary engines. The peculiar construction of
the compensating engines was illustrated by several models
and detailed drawings, showing the peculiar action of the ex-
pansion valves, and the two pistons in each cylinder. The
great difficulty encountered appeared to have been in the valves
of the air pump, which were destroyed by the extreme rapidity
of the action ; this was provided for by constructing an air-
pump without valves. By a peculiar arrangement of the air
and water passages, it became practicable to substitute for the
ordinary cover a piston travelling through a very limited space,
and for the air-pump bucket a solid piston travelling the full
length of stroke. The valves were thus done away with, and
the action of the engine became complete. This construction
has been adopted with great success on several stationary and
locomotive engines, and is now being applied to marine en-
gines, to which it is peculiarly applicable, as it is of great im-
portance to be enabled to work the Archimedian screw pro-
peller without the insertion of bands or wheel-works.
Mr. J. Woods exhibited and explained the action of Sie-
mens' chronometric governor. The centrifugal governor of
Watt being acknowledged to be an imperfect instrument, in
consequence of its inability to adjust the valve to the altered
circumstances of the load of the engine, Mr. Siemens in-
vented the chronometric governor. The new instrument
was stated to have been at work successfully for some time
at Carpenter's corn-mills, Shad Thames. It consists chiefly
of a heavy pendulum, which is allowed to move to a
certain arc of vibration of chronometric revolutions, and
it is connected with the horizontal pinion above, which
therefore moves in union with it; an endless screw is
geared in conta .t with the horizontal pinion, and is
drawn by a constant weight in a horizontal direction ; it has
therefore a tendency to produce a revolution of the pinion and
pendulum. This horizontal screw must be turned by the engine
at the exact velocity necessary to insure its running in gear
with the pinion, driven at the constant velocity, dependent on
the length of pendulum ; and should the engine succeed in
turning the screw at the proper velocity no horiz ,ntal move-
ment will take place, and the weight on the lever before-men-
' riooed, continues a constant driving power, independent of the
engine, for overcoming the existence of the atmosphere and the
fiction of the pendulum. It the load, or the supply of power,
varies, a tendency to alter the speed of the horizontal shaft im•
mediatety commences, and it takes up a new position, by having
travelled faster, or slower, than the pendulum and its pinion,
and it retains this altered position, and consequently the ad-
justment of the Valve, by means of appropriate connecting
levers, until the conditions of equilibrium of load arid power
are again varied.
The action of this governor is so sensitive, that no variation
of the speed of an engine, when 40 per cent. of its load is
thrown off, can be observed, for the entire change is per-
lormed in one-fiftieth of the revolution of the fly-wheel; this
change absorbs or adds a portion of the momentum of the pen-
dulum, and slightly alters its are of vibration, the limit of which
is between eighteen and twenty.one degrees, and by the laws of
pendulous motion this is shown to affect the number of revo-
lutionspanendd ulurmo
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This being the last meeting of the present session, Cir Jonx
RENNIE, president, addressed the members, with congratula-
tions on the interesting character of the papers read, the dis-
cussions at the meeting, and the very full attendance of mem-
bers and visitors, and impressed upon them the necessity of re-
doubled exertions in future, in order to support adequately the
i
elevated position to which the nstliution has attained.
Mr. WALKER., in a speech full of kind feeling, proposed a
vote of thanks to Sir John Rennie, for his devotion to the
duties of president, his uniform attendance at the meetings,
and the kindness and hospitality he invariably displayed to the
members, collectively and individually.
The ballot of the session took place, and the meeting ad-
journed until the second Tuesday in January of the ensuing
year.

COLOSSEUM, REGENT'S PARK.—The following dis-
tinguished persons were among the visitors to the Co-
losseum during the early part of the week:—Duchess o
Sutherland, Duke and Duchess of Buccleuch and party,
Marchioness of Donegal, Marquis of Exeter, Earl and
Countess of Dunraven, Earl of Uxbridge; Lords Leigh,
Harrowby, Manvers, De Lisle, Carnarvon; Sherbcrne;
Lady Middleton, Lady Peel and party, Lady Strad-
broke, Lady Canning, Mi,s Burdett Coutts, Etc.
LOUISIANA SUGAR.—The Lords Commissioners of
her Majesty's Treasury having had under consideration several
applications from parties who have imported sugar the growth of
Louisiana, with certificates of origin under the hand of Mr. Mure,
her Majesty's Consul at New Orleans, such certificates not being
in formal and regular compliance with the requirements of the
statute, and their Lordships having, in these several cases, con-
sidered that the attention of the shippers, in all probability, had not
been drawn with sufficient precision to the terms of the statute,
have been pleased to permit the admission of the said sugars at the
lower rate of duty, and have communicated with the Earl of
Aberdeen, Secretary of State for Foreign Affairs, on the subject,
with a request that his Lordship will make known to Mr. Everett,
the American Ambassador, their Lordships' intention to require
in future a strict compliance with the law. Their Lordships have
therefore been pleased to direct, that certificates of origin, under
the hand of Mr. Mure, being in the same form as those already ad-
mitted, and not otherwise objectionable, be admitted up to the close
of the month of June ultimo, but that from and after the first day
of July inst. a strict and regular compliance with the provisions of
the law in respect thereto, will be insisted upon in every instance.
This orcer is of considerable importance to the sugar trade and
importtrs of the article, and has been communicated to the
revenue departments of this port, Liverp..ol, Bristol, and other
Forts of the kingdom, for the inforivation and government of the
officers and all parties concerned.
FATAL RAILWAY ACCIDENT. MANCHESTER,
MovoAy.—On Saturday morning an accident occurred on the
Manchester and Bolton Railway, by which one man was killed, and
several others severely injured. It appears that one line of the rail
has been taken up for repairs, and that the engines at this particular
plane have been driven to and from Bolton on the same rails.
This morning a luggage train left Manchester at an early hour,
and at Ringiey, where the rails are taken up, came into collision
with a down train with fearful violence. The engineer, on per-
ceiving the other train coming down, threw off his steam and
jumped off the engine. The fireman, who was on the tender, also
jumped off, but by some means missed his leap, and was thrown
back under the train and was killed. In the afternoon an inquest
was held on the body of the deceased, when the jury returned a
verdict of Accidental Death. None of the others injured are in a
dangerous state,