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form of the Saxon arch, wide enough to compared with the furthest extremity. When the allow of some lateral action or oscillation,

oven is charged, the entrance is closed with a wet

bundle of straw. By this arrangement the steam is so that the whole pressure will be on the driven down on the bread, and a golden-yellow crus: centre of the arch, whose base is never in is given to the bread as if it had been previously cotended to touch the platform of the rail. By

vered with the yolk of an egg.-Annals of Che

mistry. this means side friction would be avoided,

The Perlevesian Spectacles.-Such is the name for the tendency would always be to resume given to a new description of spectacles, manufacthe centre of the wheel, and such a form

tured by Ward, of the Quadrant, and remarkable

for their extreme elegance and lightness (whence would render it nearly impossible for the

the naine.) A pair of good sized glasses weighs carriages to get off the rail. According to only about a quarter of an ounce. The pebbles this plan we should also save the expense of

have grooves made in them all round their peritransverse pieces of timber kyanized and

pheries, for the reception of the frames, and it is by

ihis means the ingenious maker has been enabled pitched, together with the cutting, fitting, to reduce the weight so considerably. screwing, and bolting, and the frequent ne

The late Shipwrecks.- Many of the lamentable

shipwrecks, which have of late been so frequent on cessity of from time to time screwing up

our shores, might to a certainty have been averted, the bolts. I should recommend a space of if the vessels had been provided with the marine from 5 to 7 feet between the rails. Its fur thermometer, for which the admiralty have lately

awarded the inventor, Mr. Clement, a grant of ther advantages are, its simplicity, its in

2001. The Reliance, for example, is stated to have trinsic value, its portability, and its great gone on shore in the night, but “when the wind safety.

was fair," and it is inferred that "they could nerer By the assistance of a friend who is a

have seen the land;' that is to say, that they had

lost their reckoning and did not know where they good calculator, and concerned in an iron were. Now if there had been a marine thermometer foundry, I find the price of the castings, at on board, this admirable instrument would have the present price of iron, would amount to

indicated amidst the thickest darkness their apthe following sums.

proach to the rocks, in ample time to have enabled

them to steer clear of them; and thus, at an exThe transverse piece in one casting will pense of some 401. or 501. the lives of 113 persons, weigh 15 cwt. 2 qrs. 2 lbs., at 41. per ton,

and property estimated to be worth 250,0001. might

have been saved. So also with the brig Hamilton, 31. ; one at every 10 feet is 528 in a mile,

wrecked on the Gunfleet sand: the weather was which, at 31. each, is about 1,6001. per mile. "exceedingly foggy; about four o'clock the word Rails at 50 lbs. weight per yard, and at 61.

was • breakers ahead,' and almost instantly she

struck on the sands." With the marine thermoper ton of rolled iron, comes, per mile, to

meter no such disaster could have occurred; the 4701. ; and thus the expense of the iron navigator can steer his way with it as safely, (so far work, per mile, is 2,0701.

as rocks and sands are concerned,) as in the clearest

sunshine. I must not forget to add, that the wheels

We hope that ere long not a vessel will

be allowed to go to sea without one of these unof the working steam-engine should be so erring guides on board. constructed, as to have a bite base line of To separate Silver or Gold from Lead.--Take a the rail, in contradistinction to the carriage

few grains of bone ash, make it into a paste with a

little saliva, spread it about one line thick on a trains, whose weight would only press on piece of charcoal, and make a shallow impression the rounded part of the rail, at their centre, in it, to receive the globule of metal. Expose it to and whose flanges are never to touch the

the heat of the blowpipe, so as to burn it white and

hard, and then melt the globule of the alloy on it, base.

and keep it in a constant red heat, till the lead is all I remain, Sir,

oxidised. The advantages of the bone ash over the

mica sometimes employed are manifold. 1. It is Your obliged humble servant,

easier to be obtained, and everywhere the operator G. CUMBERLAND, Sen.

can prepare a little if he should not be supplied

with it. 2. The metal will remain in the concavity November 9, 1842.

of the bone ash paste, and not be liable to run down and be lost, as on the mica. 3. It is never necessary to change the material; the bone ash absorbs the litharge which collects on the mica, and im

pedes the process, so that the remaining metallic NOTES AND NOTICES.

globule has to be transferred to a fresh slip of mica Steam-baked Bread.-It has been known for some 4. The colour of the paste, after the operation is time at Vienna, that if the hearth of an oven be finished, gives an indication as to the nature of some cleansed with a moistened wisp of straw, bread impurities of the metal; lead alone makes it appear baked therein immediately afterwards presents yellow; a small proportion of copper changes this a much better appearance, the crust having a beau yellow colour to greenish.-Dr. G. Engelmann. tiful yellow tint. It was thence inferred that this peculiarity must be attributed to the vapour, which

INTENDING PATENTEES may be supplied being condensed on the roof of the oven fell back on the bread. At Paris, in order to secure with cer

gratis with Instructions, by application (posttainty so desirable an appearance, the following paid) to Messrs. J. C. Robertson and Co. arrangement is practised :-The hearth of the oven

166, Fleet-street, by whom is kept the only is laid so as to form an inclined plane, with a rise of

COMPLETE REGISTRY OF PATENTS EXTANT about eleven inches in three feet, and the arched roof is built lower at the end nearest the door, as from 1617 to the present time).

LONDON : Edited, Printed, and Published by J. C. Robertson, at the Mechanics' Magazine Office,

No. 166, Fleet-street. --Sold by W. and A. Galignani, Rue Vivienne, Paris;

Machin and Co., Dublin; and W. C. Campbell and Co., Hamburgh.

MUSEUM, REGISTER, JOURNAL, AND GAZETTE.

No. 1007.]

SATURDAY, NOVEMBER 26, 1842.
Edited, Printed and Published by J. C. Robertson, No 166, Fleet-street.

[Price 6d.

Double.

IMPROVED PLAN FOR WORKING THE SLIDE-VALVES OF HIGH

PRESSURE STEAM-ENGINES.

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STEAN

IMPROVED PLAN FOR WORKING THE SLIDE-VALVES OF HIGH-PRESSURE

ENGINES. Sir,—As you are always willing to re valve-plate; b, rocking-shaft; cc, its ceive any thing new, I take the liberty of supports ; d, waste steam-pipe; HH, sending you an accountof my invention for steam-passages to the cylinder; G, lever working the slide-valves of high-pressure fixed to the rocking-shaft, and working engines, without a stuffing-box and valve upwards through the centre of the educrod, thereby dispensing with the usual tion aperture, as in fig. 1; F, end of set of levers and guides, and the continual rocking-shaft, to fix hand-gear and ecpacking and great friction attending stuff centric lever for working the valve, as in ing-boxes of every description.

fig. 3.

will be seen that one end of the Description of the Engravings.

rocking-shaft passes through the waste Fig. 1. A, the cylinder; B, the pis steam-pipe at e; but as the steam there ton ; C, valve-box; D, valve; E, steam is not very strong or much valued, a pipe from boiler; F, waste steam pas common well-finished brass step will be sage, made sufficiently large to allow thie found sufficient. By inserting the above steam to escape freely, and the spanner, in your valuable Magazine, you will G, fixed to the rocking-shaft, H, to move greatly oblige, backwards and forwards; I, eccentric

Yours, &c., rod, taking hold of the lever J, fixed to the end of the rocking-shaft; K, square

ROBERT H-LE. hole in the centre of the valve-cup, to P.S.—The above plan promises to be admit the end of the spanner, G, to work valuable for locomotive engines, as it ad. the valve.

mits of the eccentric rod being connected Figs. 2 and 3 show more clearly the direct from the crank-shaft to the valverocking-shaft and its supports. aa,

lever.

ON THE LATE PARIS AND VERSAILLES RAILWAY ACCIDENT.

BY BENJAMIN CHEVERTON, ESQ. Sir,- Notwithstanding the official re the fact, but failed to draw any important ports of public functionaries, and the inference from it; thus additionally illusscientific investigations—in popular esti trating the difference between practical mation, at least, so accounted-of the and mere scientific acumen, in the investi. learned members of the French Aca gation of such matters. The failure of the demy, it was reserved, it appears, for

fore-axle having most conspicuously atthe Mechanics' Magazine to give the tracted their attention, they indolently only satisfactory and intelligible state took it for granted, that this was the first ment, in regard to the probable origin event in the course of the accident; and and course of the accident on the Paris that the indentations must have arisen and Versailles Railway ; and the inform from a subsequent ploughing up of the ation, most appropriately, has been furnish road, by the deranged appurtenances of ed by a Practical Engineer.” And yet, the broken-down engine. if your correspondent's account of the ac It appears, however, that there was cident be correct, (and really there is a sa among the French engineers one acute tisfying prima facie truthfulness impress observer of minute facts and apparendy ed on every particular of his statement,) it is trivial circumstances--a man who, in the surpassing strange, that men making any true spirit of practical talent, was dispretensions to the faculty of seeing, or posed also to arrange and combine the assuming credit for the slightest talent information thus obtained, so as to make for observation, should have overlooked the inference irresistible, that the engine the fact indicated by the indentings of left the rails with the fore-axle, at least, the sleepers, that the engine had run off entire---that subsequent to this, if not the rails a considerable distance pre before, the engine was in a state of vioviously to its complete overthrow. It is lent oscillation, both lateral and vertical just possible, indeed, that they did notice -and that it went bounding on in this

way, over the sleepers, a considerable others gave way, the want of equilibrium, distance, until the tremendous shocks if not determined at once by the inequabroke the fore-axle and brought all to lity of weights, would be quickly deterthe ground. This statement clears up mined either by the tug of the engine or most of the mystery about the accident: the push of the train, according as the it satisfactorily accounts for the failure of one or the other of these causes was the fore-axle, hough the iron, by ac brought into action, through the failure knowledgment, was of the best quality ; of the fore or of the hind axle, as the and it particularly explains how it came case may be. to be broke at both ends. This event There is, however, one important point is now seen to be the last, instead of the not yet cleared up, which is this: did the first of the series, as assumed in the of- leading locomotive leave the rails in conficial investigations, and as taken for sequence of a failure occurring in any granted on such authority, in all the part of the engine, or in consequence of subsequent discussions.

oscillatory motions ordinarily induced ? But how was it that no notice was The latter is the conclusion come to by taken, by the authorized reporters upon your correspondent, and probably also the accident, of the observations and in- by the French engineer whose investigaferences made by this engineer? Did tions he has recorded; but it does not he not come within the purview and cog appear to me that the evidence is in favour nizance of official and scientific dignity; of it, but leads rather to the opposite or were those personages really incom- opinion. It must indeed be allowed, petent, however mathematically clever, that the existence of very violent oscilto appreciate inductive truth, or the lations both vertical and lateral, after manner of its evolution, through a mate the engine left the rails, is unequivocally rial investigation of physical incidents, proved, by the alternate indentations of even when presented to them by others ? the wheels on the sleepers, and by the It is surely better to impeach their saga sinuous lines so traced. It must also be city than their integrity, in a matter admitted, that this freedom of oscillation, of so much importance, and thus save and the measured correspondence of the them from the imputation of a design to indentations with the width of the wheels suppress information on a subject on apart, are, both of them, incompatible which the lives of thousands may depend with a complete fracture of either of the on its being thoroughly and faithfully in- axles ; or at least with any very deranged quired into, while time and circumstances position of the wheels in consequence of permitted M. Combes is a good mathe it. It must be further admitted, that matician, and can give mathematical, if these oscillations could not have comnot practical formulæ for the velocity of menced all at once ; and it may be ada current of air in the ventilation of mitted, that they existed some time premines; he is, moreover, the superintend- viously to the locomotive leaving the rails, ing government engineer of steam-en increasing gradually in violence to such gines in the department of the Seine ; an extent, as to induce M. Milhan to but in spite of all this, and in spite of the sound the alarm whistle, and Mr. George very best Ecole Polytechnique attain to apply the brake.

But still the quesments, into which a man can be drilled, tion arises, whether these were not the he does not appear to have been aware, ordinarily induced oscillations, and not of that a six-wheel locomotive will as surely themselves sufficient to have forced the come to the ground as a four-wheel en engine off the rails ? Whether in fact gine, in case a similar accident happens something else did not occur, in concurto its fore-axle as that which he supposes rence with, and perhaps also in aggravaoccasioned the late disaster ; for he says vation of, these oscillations, to occasion in his report, what a little practical good the wheels to leave the rails? Now we sense, if not common sense, would have know that the following incident occurred, informed him to the contrary, that, “ if possessing an aptitude to stand in the one of the axles (provided six wheels are relation of a cause to the accident, wheadopted) should break, the carriage would ther it actually did so stand or not, still rest on supporters, and continue its namely, that Mr. George suddenly apcourse.” This would be true only in the plied the brake immediately previous to contingency of the working axle being its occurrence. the one that failed. If either of the

I 12

I endeavoured to show in a former cranks was with equal suddenness necesarticle, (No. 981,) that the suddenness sarily caught at, or very near to, a right and force of this application may have angle with the connecting rod, and thus thrown a stress of so instantaneous a na the steam being on, the axle was acted ture on the axle, (not knowing at the on by a double force, transverse and tan. time which axle had given way,) as to gential, to the effect of both bending and occasion its fracture, and that thus the twisting it at one end. Thus the appeare disaster had occurred. Subsequent in ance of torsion was produced, and it is formation, chiefly furnished by your cor not an appearance likely to mislead), alrespondent, a “ Practical Engineer,” though the complete fracture it is probable whilst it obliges me to modify, in some only took place on the overthrow and col. measure, this hypothesis, confirms, I lision of the engines. Neither could the think, its accuracy, as to the orgin of the axle have been much bent, otherwise accident being in the application of the the derangement of the wheel on that brake. The fracture of the fore axle side would have been greater than it apin two places is now amply accounted pears to have been; but it was sufficient, for, but the breaking of the driving axle I conceive, to constitute that accessory is not so easily understood. It must circumstance, which in aid of the violent either have been a mere casualty (another lateral oscillation, occasioned the wheels name for obscure causation and our own to surmount and leave the rails. It is ignorance,) or it must have taken place easy to see how this effect would be proat the overthrow of the engine; or it must duced, and how in the operation the rail have been produced by the brake. The on that side would be forced into the first supposition is quite a chance, and very sinuous state" described by your unlikely to occur at a time when the correspondent, for the tendency would be, working strain on the axle could not have so to bend the axle at the journal on the been great; the second, also, is a very side where the torsion took place, as to improbable occurrence, except so far as place the wheel at a slight horizontal dithe shock and collision may have made verging angle with the rail. Hence the a complete fracture of a previously crip indentations on the sleepers, (the wheel pled state of the axle; for it is particu. being retained in that position by the larly to be observed, that the axles, nei brake), would not be observably different ther of the accompanying tender, nor of from the proper distance of the wheels the six-wheeled engine and its tender, apart; hence also the increased inclina. were broken in this melée. Besides, it tion to run off the rails; and hence the is expressly stated in the report, that intermitting sort of displacement of one “the fracture appeared to have been pro rail only from the straight line, as the duced by torsion.Only the third sup oscillatory movement upon it took place. position, therefore, is probable, and it It appears also that the rail in this prealone furnishes an adequate cause for the dicament was the right hand rail of the effect. There must have existed in some right hand line of rails, looking towards manner an obstacle to the rotation of the Versailles; and it might have been ascerdriving wheels, equal in its force of re tained at the time, if that full investigasistance to the power of producing torsion tion of the minutest particulars had been in the axle. Now I cannot conceive instituted, which the importance of the anything in the way of friction from the subject demanded : whether or not this ground, or from carriages in contact, was the rail which would be displaced, as that could have furnished such resistance. corresponding to the position of the brake, Nothing but the means expressly pro if but one; or to the side on which Mr. vided in the brake, for putting a com George was standing, if there were two; plete stoppage to the revolutions of the or the crippled end of the axle, if, as is wheels, would be sufficient for the pur most likely, the crippling and ultimate fracpose.

ture took place on one side. The several It appears to me that the application circumstances here noticed, coinbined and of the brake operated in this manner : harmonised, strongly warrant the inferAt the same moment that an instantane ence I have drawn, that the locomotive ous strain was thrown on the driving was forced off the rails by an accident axle, in the form of a retarding force to supervening upon a state of oscillation ; oppose the mass in motion, one of the and that the origin of this accident, and

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