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Effective Mean Pressure in the Cylinder for Various Admissions.

For Maximum Pressures of 60 lbs. to 150 lbs.

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In all well protected cylinders, with blast orifices not less than 1th of the area of the cylinder, the foregoing rules and tables of data apply to the action of steam at speeds under 30 to 40 miles an hour, as the writer has fully shown in his work on Railway Machinery. For speeds amounting to 55 to 60 miles an hour, the loss by imperfect exhaust causes a large increase of consumption per horse power per hour, of from 33 to 12 per cent., according to the amount of admission. With steam ports of about 14th, and blast orifices 14th of the cylinder, the rules likewise apply, at speeds under 30 to 40 miles an hour. At the higher speeds, the useful power is considerably impaired by imperfect exhaust.

The proportions of the Great Britain, from the performance of which the foregoing results are deduced, may be repeated here as standard ratios for practice, until superior results are obtained.

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Lap of valve, 14 in.; travel, 4a in. in full gear; lead, ‡ to § in. In a second paper, the writer discusses the conditions necessary for the successful expansive working of steam in locomotives. The following is a comparison of the actual results of engines working with ordinary gabmotions and with link-motions. The engine Europe, on the Edinburgh and Glasgow Railway, cylinder 16×18 inches, wheel 6 feet, doing one week's work in 1849, with gab-motion, consumed an average of 19 cwt. of coke per day, and 2 cwt. of coal. As, in the locomotive boiler, coal is about two-thirds of the value of coke, 2 cwt. of coal is equivalent to 1.33 cwt. of coke; and the consumption per day may be stated at 20-33 cwt. coke.

The same engine, fitted with link-motion, used at the same season in 1851, and doing the same work, 12 cwt. of coke, and 3 cwt. of coal daily, equivalent to 14 cwt, coke. Over a run of 94 miles, the expenditure becomes

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The periods of admission in the two cases would be about 70 and 45 per cent., and by the table of efficiency the consumption would be as 1.50 to 1.23, showing an economy of only 18 per cent., or barely two-thirds of what was actually made. The greater actual efficiency must in great part be due to the superior opportunity of working with high pressure, during the admissions offered by the link.

Again, the test may be applied by measuring the water consumed. The following are a selection of cases from the writer's own experience and

observation:

Engine with Link-motion; cylinder, 15×20 inches; wheel, 6 feet. Edinburgh and Glasgow Railway.

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Engines with fixed Gab-motion, cylinder 16 X 18 inches, wheel 6 feet. Edinburgh and

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Express engine, with fixed Gab-motion; cylinder, 16 x 18 inches; wheel, 6 feet. North

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These results show, as before, that under similar circumstances, what has been deduced from an independent examination of indicator diagrams, taken under the link-motion, as to the economy of steam worked expansively, is fully borne out by a direct appeal to the relative consumption of coke and water.

(To be continued.)

For the Journal of the Franklin Institute.

Description of Lahaye's Patent Self-Acting Brake.

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Operation of Brake, Fig. 1.-The car is supposed to be coupled to an engine, by the pulling bar d at c. Immediately on the steam being shut off, the momentum of the car and train behind it presses the pulling bar upon the engine at c; this pressure is communicated by a shoulder in d, through the shaft e, pulling rods g, springs h, and tie rods i, to all the brake blocks, causing them to act upon all the wheels with a force proportioned to the resistance at c, and ceasing only with the latter resist

ance.

Operation of Detaching Levers, Fig. 2.-The brake blocks are supposed to be pressed against the wheels, the engine reversed, the train stopped, and required to be backed. The wheel B, fig. 2, turning in the direction of the arrow, moves the brake block, l, upwards in the same direction, carrying with it the lifting bars, n, acting upon the bell cranks, o p, detaching rods, q, and crank, r, thus moving the tongue, s, upwards, and ungearing the pushing bar, d, allowing the car to be moved backwards by the bar, d, pressing against the ring bolt by a slot in d, through which said ring bolt passes.

General Remarks.-The detaching motion is instantaneous in its action. The ordinary hand brake can be applied to every car with the self-acting brake, and acts independently of the latter. When it is not required to back the train, the pressure of the brake blocks is relieved immediately by the forward motion of the pulling bar, d.

The chief advantages of this brake are as follows:

1st, It is self-acting, operating only when it is desired to stop the train or diminish its speed, and relieving the wheels of its pressure instantly, on the cars feeling the forward or backward motion of the engine.

2d, Its action is instantaneous on every car in the train, commencing the moment the steam is shut off the engine, and ceasing only with the motion of the cars.

3d, Its power is exactly proportioned to the necessity for the gradual or sudden stoppage of the train, resulting from the judgment of the engineer in the management of his engine; the brakes acting with moderate force when the steam is shut off the engine, with increased intensity if

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the tender brake be applied, and with sufficient force to back the wheels (if required) if the engine be reversed.

4th, It is simple in its construction and operation, not liable to derangement, and so constructed as to allow the use of the ordinary hand brake on every car, when the latter is moved separately.

CERTIFICATES.

Lahaye's Patent Brake has been in operation upon the passenger trains of the Philadelphia and Reading Railroad for several months past. It has worked to our satisfaction, has caused no expense for repairs, remaining in the same condition as when first put on, and proving on many occasions eminently useful in arresting the rapid motion of the train, when danger was observed and the engine reversed.

I consider it one of the most valuable inventions ever made to increase the safety of railroad traveling, as by its use a passenger train can be stopped in about half the space usually required.

Reading, Pa., March 16th, 1852.

G. A. NICOLLS,

Eng. & Sup. Philad. & Reading Railroad.

Mr. John Lahaye's Self-Acting Brake has been in operation on the passenger cars of the Philadelphia and Reading Railroad for several months, and its operation has been such as to give entire satisfaction. I think a fair trial of it by any railroad company will convince them that it is the only contrivance of the brake kind that can be relied on when there is a necessity for stopping a train in case of collisions.

I would recommend it particularly to railroads using but a single track; for them I think it indispensable.

Reading, Pa., March 16th, 1852.

JAMES MULHOLLAND, Master Machinist, Philad. & Reading Railroad.

Description of Pilbrow's Water Waste Preventer.*

This article, manufactured by Guest & Chrimes, of Rotherham, is introduced for the purpose of detecting and preventing waste of water supplied to the inhabitants of towns by water works, whether such waste be wilful (as is too often the case amongst the inconsiderate occupiers of cottage property), negligent, or accidental from leakage or bursting of pipes, leaving open taps, &c., and is especially applicable, and may be said to be almost indispensable, where water is supplied on the "high-pressure" and "constant-supply" system. When it is considered that under this system, at a pressure of, say 150 feet, the smallest tap in ordinary use-viz. 3-inch-will, if left open for only one night of ten hours, waste from four to five thousand gallons of water, it will be most manifest that any article which will prevent a waste of such serious magnitude is one that must fairly claim immediate attention, and insure extensive adoption.

The Water Waste Preventer is calculated and guaranteed not only to remove this difficulty, but also to obviate the necessity of stop-cocks, as these will be no longer required for the purpose of shutting off water whilst repairs are being made to taps and pipes in consequence of leakage, the removal, or repairs of broken taps or service pipes, bursting of pipes from frost, or any other ordinary cause.

From the London Civil Engineer and Architect's Journal, May, 1852.

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