The prefixed drawing represents the frame of a locomotive engine carriage, the wheels of which are of a compound description, having teeth or cogs on the inner side, and made in the ordinary form on the outer side, with a rim or flange in the centre: the iron railway on which it is intended to traverse does not differ in any respect from the most approved rail in use, so long as the line is perfectly horizontal; but, when it is desired to change the level of the railroad, a compound rail corresponding with the wheels must be laid down, at a suitable angle (about one yard in ten), so that the wheels of the locomotive-engine may be then assisted by the cogs: these cogs should also extend on the horizontal line both above and below the angle required to the full length of any train to be drawn on the rails, in order that the engine may have the assistance of their fulcrum until the last carriage has passed the angle of ascent. And when descending, the cogs must in like manner extend on the lower level to the same length for the purpose of enabling the engine to support the train until the last carriage has again reached an horizontal line. In all cases the weight of the carriage rests upon the plain surface-the cogs merely acting as fulcrums to assist the engine. I prefer the cogs to be made of wrought or beaten iron.

A comparison has been urged in favour of stationary-engines over the plan now shown.

1st. The outlay for the erection of stationary-engines is one item of consider able expense.

2dly. In many situations the coal is very expensive, and all that is consumed must be to the full value thereof an extra expense.

3dly. An establishment of engineers and firemen at every station is also an extra and constant expense. The delay of attaching and detaching the trains (gránting the steam to be always in readiness), and the possibility of the breaking of chains or ropes are contingencies worth consideration.

This plan offers the advantage of such strength and simplicity, that no engineer can possibly make a mistake in ascending; for he has nothing to do, nor will the train be required to stop one moment.

always ready, and the action of the cogs follows the plain surface imperceptibly. In descending, the engineer has only 10 turn the handle of a screw, which acts upon powerful breaks on both axles, so as with ease to stop the whole train in the middle of a descent if required, or to regulate the speed with the greatest precision.

It cannot be necessary to say one word upon the enormous saving of expenses in laying down railways which this mode affords; nor upon the advantages of avoiding both tunnels and embankments. Kilsby Tunnel on the Birmingham line, and Chat-Moss on the Liverpool and Manchester, are specimens of the fearful expenses to be encountered. Noblemen and country gentlemen are quite able to judge of the effect of a long line of embankment in the prospects from their mansions, and on their sports in the field.

These brief remarks are only intended to draw attention to a plan which it is hoped has merits sufficiently obvious to meet all objections which may arise from interested motives only. To bona fide shareholders the possibility of saving one million sterling out of three, must be an bject worth their consideration.

Description of the Engraving.

AAA represents the ordinary horizontal rails; B, iron rails, baving, in addition to the ordinary smooth surface, an inner line of teeth or cogs, and laid down at an angle of 1 in 10, which combined rail must be continued above and below the rise required to the length of any train of carriages which may travel thereon, and the cogged or toothed part must feather off at the extremities; C, a frame on which a locomotive-engine would rest; DD, iron wheels, having the inner side cogged, and the outer side plain with a rim between; EE, breaks, attached to one or both axles, to regulate the speed when going down hill.

HENRY W. WOOD.

29, Austin-friars, London,

[We publish Mr. Wood's "Improvement in Locomotive-Apparatus" from a desire to let the mechanical world know every thing, of even apparent uti lity, which has been proposed for readering either more economical, or more effective, the grand system of national intercourse to which it relates, rather

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than from any high opinion of its merits or of its originality. The plan of" mixed railways" has already been proposed and discussed in our Magazine some years ago. We refer Mr. Wood, and whoever else it may concern, to an arti cle in vol. xiii. p. 265, in particular. The following extract from this article will show that there is nothing new -in Mr. Wood's plan:-"It consists in -the mere addition to the outward edges of the rails on inclined planes of a raised flange or range of cogs, and of corresponding cogs on the power-wheels on the locomotive-engine, at a proper distance from the rim of the wheels to work in the interstices of the cogs on the rails." Several methods of applying the suggestion followed, and, amongst others, one by Messrs. W. and J.. Hopkinson, which is almost a fac-simile of Mr. Wood's (see vol. xiv. p. 120). See also the same volume, pp. 24, 159, 213, and 304. A plan very similar was also communicated to us (though not for publication) several months ago by Mr. Tait.-ED. M. M.]

"HOUSE-BURNING SYSTEM."

Sir, Facts are universally acknowledged to be very stubborn things, I have therefore sent the following for Mr. Baddeley to digest (if he can) during the leisure of the Christmas holidays :

"Destructive fire at Messrs. Faulkner and Owen's cotton-spinning factory, Manchester. When Mr. Rose, conductor of the fire-police, arrived with the town engines, he found the whole of the upper part of the factory one volume of living fire, and the flames spreading with the utmost rapidity. The people were hurrying, men and women nearly naked, and their children clinging to them in terror, were seen only now escaping from the fatal pile. When the engines arrived, none of the disposition to aid the firemen, which ordinarily exhibits itself among the people, was manifested by them; they stood entirely aloof, and if at all asked to give a helpinghand, remained either doggedly silent and inactive, or vented some unfeeling expression against Mr. Faulkner. The loss of property is estimated at from 10,000l. to 15,0001Manchester, Dec. 10."

Good, Mr. Baddeley; would any entreaty for assistance have been necessary to this cold-blooded vindictive mob if Mr. Braithwaite's steam fire-engine had

been the town's engine instead of the (in this case, at least,) useless squirts they possessed-au contraire, without any appeal to such scoundrels as must have coinposed that mob, and may compose others hereafter, in Manchester and other great manufacturing towns, where differ ences exist between master and workman

Swing" having stepped in to aid the Jatter in his system of intimidation→ the steam fire-engine would, without aid being required from any, have done its work nobly, and been the means, probably, of saving considerable property.

Oh, Mr. Baddeley, may we be delivered from such fire-extinguishers as are the different companies which you have taken under your steel (pen's) protection-they are unworthy of your talents-give them up, or they'll drown you for pure love some day in one of their buckets.

I am, Sir,

Your obedient servant,
FIRE-FURY.

THE RELATIONS BETWEEN THE PUBLIC AND INSURANCE-COMPANIES FURTHER

EXPLAINED.

Sir, I am sorry I cannot congratulate "Fire-Fury" on the clearness of his perceptive powers, in return for the title and compliments he has lavished upon me in your last Number; had he carefully perused my communication on the relation in which the public and the InsuranceCompanies stand to each other, at p. 157, he would have found a clear and explicit answer to all the questions, which he has thought proper to put to me at p. 179. However, I am extremely anxious that every person should fully understand what these simple relations, in fact, really are; I, therefore, willingly take up my pen to endeavour, if possible, to put the matter in a still clearer point of view. To question the first (vide p. 179), from my own personal knowledge, I answer YES. The formation, by the InsuranceCompanies, of the London Fire-Establishment, and the history of its proceedings and performances for the past four years, establishes this fact. Every nerve has been strained to render the Fire-engine Establishment as efficient as possible; numerous improvements have been introduced from time to time-many

replies to their circular were canvassed in their meetings, and finally laid before the public. It occurred most opportunely for the ultimate success, though not for the rapid completion of their labours, that an opportunity was afforded them for experiment, by which to test many of the suggested causes of, and preventives to, the explosions of steam-boilers.

These experiments, originally proposed by our public-spirited fellow-citizen, S. D. Ingham, Esq., then Secretary of the Treasury of the United States, have been brought to completion, and presented to the public under the auspices of the present secretary.+

The Committee trust that they have, by the experiments just referred to, shown not only what are some of the causes of explosion, but, which is quite as important, what are certainly not causes. In this way they hope to have turned away the attention of ingenious men from false hypotheses which cannot furnish the remedies they are in quest of, and to have pointed out some directions in which their labours may be profitably bestowed.

A desire to complete the reports upon their experiments, has induced a delay in the present Report, which, thus far, however, the Committee are satisfied will be found to have been judicious. This conclusion they rest upon the many references, which will appear in the following pages, to those experiments, which have given an authority to recommendations and suggestions, that could not have been claimed for them unless thus strongly supported by facts.

They regret much that the part of their Report referring to the strength of materials will, from circumstances, be unavoidably incomplete. This deficiency, they hope, will hereafter be made up, the experiments on the subject having been some time since concluded; and they do not feel warranted, by this cause, in any longer delaying their general Report.

In this Report the Committee have endea voured, by examining the different accounts of explosions on record, and the writings on collateral subjects, to ascertain what causes have been operative in producing these disàsters. The difficulty of procuring satisfac

As these replies will be frequently referred to in what follows, it is proper to state here, that the references are made to the pamphlet distributed by the Committee to their correspondents and others, and that Nos. 1. to XIII, both inclusive, were published in the Journal of the Franklin Institute of Pennsylvania for the Promotion of Mechanic Arts, Vol. VIII.; Nos. XIV to XXVIII., both inclusive, in the same Journal, Vol. IX.; No. XXVIII. Part II., and No. XXIX., in Vol. X.; -and No. XXX. in Vol. XI.

Hon. Levi Woodbury, for whose promptness -in forwarding their views, the Committee beg leave here to return thanks.

tory testimony in regard to them, has been often pointed out. Most frequently those from whose mismanagement or want of vigilance they have immediately resulted, have been victims to them, and when they have survived, the precise state of things before the occurrence was imperfectly known to them; and, however honest, their minds have received a bias towards the non-existence of certain circumstances judged likely to have produced the results.

It hence follows that in regard to many explosions, either none of the circumstances which immediately preceded them, and bearing upon them, are known, or by inaccurate statements of them, an appearance of mystery is thrown around the whole matter, calculated to baffle research, and to alarm the community, who are exposed to a recurrence of the same dangers. Thus it happens that of the numerous explosions on record, few are made to subserve the cause of humanity, by a knowledge of their proximate causes. The details of the number of killed and wounded, and of the more or less entire destruction of the boilers and of the boats, are given in the daily prints, and public cu riosity is satisfied.

In making their examination, then, of the cases of explosion, the Committee have selected such as they have found most directly to the points in support of which they are cited; omitting others in which the facts are less clearly made out, or in which the causes assigned may be resolved into matters of opinion. Having themselves no theory, or theories, to support, they have of course not been biassed, by such views, in the selections made.

This mode of proceeding is, obviously, not calculated, by one effort, to exhaust a subject. But the Committee believe, that they are able to make a decided step forward in the knowledge at present existing, in a connected form, on this subject. That to the causes pointed out by a Committee of the British House of Commons,‡ in 1817, namely, improper construction or material of a boiler and undue but gradual increase of pressure, they will be able to add others as important, and as fully proved as the former. Nor will any cause for alarm result from this extension, since it will be found that it is only ignorance of these circumstances which constitutes their danger, and that they may be prevented from occurring and remedied when they occur. It will be full time after the well-ascertained 'causes of explosion have been duly guarded against, to look for others more occult in their nature, if, indeed, there are such.

In the following Report, the Committee propose to examine separately the circum

Charles Harvey, Esq., Chairman.