Page images
PDF
EPUB
[graphic]

GISTER, JOURNAL, AND GAZETTE.

find it will bear a pressure on the square inch of one unit on the outside, and of two units on the inside, with safety. According to Mr. Seaward's rule, if 1 understand it rightly, another flue, the same in all its dimensions, except that it is three times the thickness of the first, should bear three times the pressure inside, and nine times the pressure outside; or a pressure of six units on the square inch on the inside, and of nine units on the square inch on the outside, which is contrary to both reason and experience. Yours &c. S. Y., An Engineer.

Railway Signal.-We have recently had an opportunity of inspecting a railway signal erected at the Grand Junction station, Birmingham, which, from its great simplicity, and the unerring certainty with which it conveys the requisite information, as to the state of the points, to the drivers of locomotive engines, both by night and day, appears to be an invention highly important, not only to the proprietors of railroads but to the public generally, as it will greatly tend to prevent those accidents which have occasionally occurred in consequence of the points (or shunts as they are called) being left in a wrong position. The invention consists of two discs, about two feet in diameter, placed at right angles, surmounted by a lantern showing four lights, but of three distinct colours, viz., two red, one blue and one white; the discs, are painted to correspond. This apparatus is firmly attached to the top of the eccentric shaft employed in moving the points, and consequently turns with it with unerring certainty, and can be seen at a great distance, affording the enginemen or drivers ample time to govern the trains according to circumstances. The signal is the invention of Dr. Church, of Birmingham, and has been patented; and there is no doubt it will soon be adopted by the railway companies generally. -Midland Counties Herald.

Opening of the London and Birmingham Railway. We are glad to learn, that, in consequence of the unexpectedly rapid progress recently made with the works of the London and Birmingham Railway, as announced by the engineer to the directors on Thursday, the opening of the line will in all probability take place a week earlier than had been previously arranged. The 17th of September, instead of the 24th, is the day now fixed upon; and, from what we have heard on the subject, we have no doubt the line will, on that day, be opened for passengers from end to end. We understand that the following are likely to be the times of departure from London, and of arrival in Birmingham, Manchester, and Liverpool:-Eight in the morning :First-class train; to arrive at Birmingham at two; start from Birmingham at half-past two, and arrive in Liverpool and Manchester at seven.-Nine in the morning:-Second-class train; to arrive at Birmingham at four; to start from Birmingham at half-past four, and arrive in Manchester and Liverpool at ten.-Eleven in the morning :-Day mail train; to arrive at Birmingham at tive; at Manchester and Liverpool about a quarter-past ten.- -Half-past Eight in the evening:-Principal mail train: to arrive at Manchester and Liverpool at seven in the morning. In addition to the above trains, which will bring passengers for Manchester and Liverpool, there will probably be two trains from London to Birmingham, which will not meet any corresponding trains in the latter town, namely, a second-class train at two, and a first-class train at four in the afternoon.-Manchester Guardian.

Improved Coach Lamps.-Messrs. Kay and John

ston, lamp-manufacturers, Edinburgh, have suc ceeded in producing a splendid article of the kind, for the use of her Majesty's mails. The form is circular, with a rather small reflector behind; a funnel and air-holes are attached for draught, which force and carry off smoke so rapidly, that dimming or dirtying the glass and plates within-the great defect of the old lamps-are very little, if at all, known. The front of the lamp is grooved, and the adjoining metallic plates so shaped, that they become in common with the reflector behind, foci of the purest lambent light. One of these lamps we saw on Saturday night, in the King's Arms inn yard, and were enabled to read a letter distinctly. In travelling from Edinburgh the road is illuminated from side to side, 100 yards in front, and of the Edinburgh mail thus furnished, it may be said, without a figure of speech, that she carries two harvest moons along with her.-Dumfries Courier.

Dangers of Steep Hills.-When expeditions travelling is the object, the rate of inclination that never should be exceeded in passing over hills, if it be practicable to avoid so doing, is that which will afford every advantage in descending hills, as well as in ascending them. For, as carriages are necessarily retarded in ascending hills, however moderate their inclinations may be, if horses cannot be driven at a fast pace in going down them, a great loss of time is the result. This circumstance is particularly deserving of attention, because the present average fast rate of coach driving over any length of road can be accomplished in no other way than by going very fast down the hills. But when the hills are very steep, and the coachman cannot keep his time except by driving very fast down them, he exposes the lives of his passengers to the greatest danger. Few travellers by stage coaches are aware of the risk they run of losing their lives in descending hills. A coachman must be thoroughly well skilled in his business, naturally cautious, and at all times sober. The wheel horses must be not only well trained to holding back, but very strong. If a pole breaks, or a pole-piece, or a haime, haime strap, or drag chain, when a heavilyladen coach is descending a steep hill, at a rate exceeding six miles an hour, an overturn is almost inevitable, by reason of the coach overpowering the horses. Hence it is that ninety-nine out of every hundred coach accidents which happen, are on hills. Nothing is more important for all turnpike trustees to pay immediate attention to, as the reducing of all hills to inclinations of at most 1 in 24.-Sir H. Parnell's Treatise on Roads.

The Compass in Iron Vessels.-The hitherto insurmountable obstacle to the employment of iron vessels in other than river navigation, has been the usefulness of the compass, in consequence of the attraction of the metal of which the vessel is constructed. Mr. Samuel Porter, in a letter to the Directors of the General Steam Navigation Company, proposes a plan by which the difficulty may be overcome. He says, "Having made upwards of 3000 of my magnetic sun-dials, and adapted them for all parts of the globe, my attention has been directed for 16 years to ths variation of the needle. I think I almost dare say, I know-if a compass were suspended by means of brass, a few feet above deck, like those in cabin ceilings, with the face downwards, even a deck as well as sides of iron would not divert the needle from that course which the Almighty has most wonderfully assigned to it there, is a point where local attraction ceases."

British and Foreign Patents taken out with economy and despatch; Specifications, Disclaimers, and Amendments, prepared or revised: Caveats entered; and generally every Branch of Patent Business promptly transacted. A complete list of Patents from the earliest period (15 Car. II. 1675,) to the present time may be examined. Fee 2s. 6d.; Clients, gratis.

LONDON: Printed and Published for the Proprietor, by W. A. Robertson, at the Mechanics' Magazine Office, No. 6, Peterborough-court, between 135 and 136, Fleet-street.-Sold by A. & W. Galignani, Rue Vivienne, Paris.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][merged small][graphic][merged small][graphic][merged small][subsumed][graphic][subsumed][subsumed][merged small]

COOPER'S (AMERICAN) PATENT RAILWAY.

(From the Franklin Journal.) Mr. Cooper's improvement consists, in part, in the form given to the upper sides of the string pieces upon which the rails, chairs or plates are to be sustained, or to the upper sides of the block of wood, or of stone, used for the same purpose; in the form and construction of the chairs adapted thereto, and in the manner of combining and connecting the respective parts together, so as to form a more stable foundation and superstructure than have hitherto been obtained at the same cost.

The patentee sometimes makes his rails by taking string pieces of a peculiar form on their upper sides, and upon these putting edge rails, by means of chairs adapted to the form of such string pieces. Fig. 1, in the drawing (see front page), shows a cross section A, of one of the string pieces of timber, and a side view, B, of a chair adapted thereto. These string pieces may be of any convenient length and size, but it will be found best to make them larger than those ordinarily used. Twelve inches in height, and two in thickness, are the dimensions preferred. It will be seen by the section that the string piece is made ridge-shaped on the top; the angle formed by the sloping sides may vary considerably, but a descent of two inches and a half on each side will answer all the purposes intended. Instead of descending from the ridge, or middle part, in a straight line, it may do so in one which is somewhat concave, or convex; the chair, in this case, being adapted thereto. The same remark will apply to the blocks of wood, or stone, hereafter to be described. The chair B, is so formed on its under side as to adapt it to the ridgeformed string piece across which it is made to straddle. Such chair, so formed, and firmly attached to string pieces, will afford greater stability, being less liable to displacement, and resisting the lateral thrust more effectually than any mode of forming and fixing such articles, now in use.

When it is desired to use a plate rail, the top of the string piece must be adapted thereto. In fig. 2, is shown a section of such a rail and plate, together with the kind of chair Mr. C. has invented, and adapted to be used with rails of that description. The upper sides of the string pieces are, in this kind of rail, sloped towards the outer edge only, commencing from a point immediately under the outer edge of the iron rail plate; C, in this fig. is the section of the string piece; D, the chair, and E, the rail plate. The chair is made in the form shown in the drawing. The chair is to be let into the string piece, so that its top shall be flush with the top thereof. There is a

shoulder offset, or jog, at a, to steady the rail plate; this shoulder may be extended up within an eight of an inch of the surface of the plate. These chairs are made of castiron of such strength as is necessary to sustain the load; they, however, will be found but little liable to fracture when properly imbedded in the rail. The distance of these chairs from each other may vary from 18 inches to 3 feet.

The dotted line shows the depth to which the chair may be let in to the string piece.

Fig. 3 represents a cross section of a railroad, and exhibits an improved mode of construction, in which the rail, or the chair which supports it, is placed upon blocks of wood, or of stone, having the upper surfaces of such blocks ridge-formed, in the same way with the string pieces first described. F, are blocks of stone, or of wood, the upper sides of which are ridgeshaped, and their lower let into the cross tie-piece G, and secured there by means of wedges H. The tie-pieces may vary in size, but abundant strength is a point of much importance: The patentee recommends having them, usually, about 8 feet long, 14 inches broad, and 8 inches thick, and then making the notches to receive the blocks 4 inches deep. The rail may be made so as to be used without chairs, in which case its form will be somewhat like that of the T rail, the lower side, however, being rolled in such a shape as to adapt it to the ridge of the block, upon which shape its stability will greatly depend. Edge rails of any of the ordinary forms may be used by employing chairs adapted to them, aud to the ridge-formed block. In a road so constructed a stone block foundation will possess the requisite elasticity, from its resting upon the wooden tie piece. If preferred, a similar advantage may be obtained by imbedding the stone blocks on a rubble foundation in the usual way, leaving their upper surface flat, and securing the tie pieces above instead of below them. The ends of the tie pieces are, in this case, to be notched, or cut, into such a form as to adapt them to the kind of chair, or rail, above described, that is to say, they must, when these are seated upon them, be ridge-formed.

ON THE CAUSES OF EXPLOSION OF STEAM BOILERS-GENERATION OF GASES IN BOILERS-BY G. H. BARTH, ESQ.

Sir, I have before me in the last Number of your Magazine, a letter from Mr. Seaward, on gas explosions as connected with the bursting of steam boilers, and request permission to offer a

few observations on the subject; not in a spirit of controversy, but cordially concurring with Mr. S., in the hope that it may lead to a full and adequate investigation of the gas theory. Should any of your readers suppose it a matter of trifling importance, I beg to remind them that if the gas theorists are not entirely in error, it is quite apparent that the means now in use to prevent boilers bursting from steam pressure, are no more efficient as a safeguard against a gas explosion than they would be against a gun-powder one.

May I ask why the idea of gas explosion has been at all entertained, or how it originated?-has it not being owing to boiler explosions having taken place, attended by circumstances which it was difficult to suppose were produced by the sudden liberation of pent-up steam, though under very high pressure. Allow me to advert, as a case, to the boiler explosion near Wigan, Lancashire, in the December of 1836, when a high-pressure engine at a coal-pit came to a dead stand; the engine-man not being able to perceive any cause, the boiler soon afterwards burst at the bottom, was torn from its fixings, and carried, or rather projected, over two chimneys, to a measured distance of 150 yards. I have conversed with persons who were present at the time, and will vouch for the truth of this statement. I cannot speak as to the exact weight of the boilerbut heard it calculated at from five to six tons. Again, see the boiler explosion at Stockport, last spring, by which nine persons were killed; in this case a heavy iron pipe was thrown completely over a five story mill, and a paving stone, or slab, 2 feet 8 inches diameter, (placed near to the boiler) through the second story window. Also a case in Derbyshire, last winter, where the top of the boiler and a mass of brickwork, weighing together more than ten tons, was projected over two streets, falling on and demolishing a frame-shop beyond. Many similar instances might be adduced-these may suffice. I conceive it difficult to show, in such cases, that the steam, when liberated, has sufficient projectile force to produce these tremendous effects; if this is allowed, the inquiry consequent is-what force then was in operation? and what the nature and capability of such force?

The answer would lead to the gas hypothesis. Before entering upon the details of such subject, perhaps, Sir, some gentleman amongst your many scientific correspondents may oblige the gas theorists by demonstrating that the presumed difficulty exists only in the imaginations of those who entertain it.

The

In the second paragraph of the letter in question, Mr. Seaward admits that hydrogen gas may be formed in a boiler from decomposition of steam, but objects, "that the circumstances under which this process may go on must be exceedingly rare, and the effect of very trifling amount." With all deference I suggest, that production of hydrogen gas must always go on with iron sufficiently heated and steam in contact. In proof of this we have the evidence of every chemist who has written on the subject since water was discovered to be a compound of hydrogen and oxygen. temperature necessary to effect decomposition of steam is generally stated at about red-heat; I am led to suppose from experiments-that it commences, though the process goes on slowly, when the iron is heated to about 700°, or even less, and increases with increase of temperature. The effects I think would depend on the structure of the boiler and fire-places, or flues in some measure, as on other circumstances also; I cannot concede they would be trifling. If Mr. Seaward will not allow the possibility of oxygen being communicated to the hydrogen -I presume that gentleman will grant, if a boiler be red-hot, and burst at, or over the fire-place, the hydrogen gas must escape, mix with the air in the flue or fire-place, and explode; would its effect then be very trifling? I do not perceive, if Mr. Seaward intended from the concluding observation of this paragraph with respect to having seen boilers partly red-hot, that they were performing their usual amount of duty at the time; if such inference was intended, and the engines condensed their steam, I will allow it to be an extraordinary circumstance, and strong objection to the gas theory, unless we could also show that sometimes red-hot iron does not decompose steam (a poser for the chemist)—or what is more likely, that iron may be sometimes protected from oxidation by an encrustation of some substance or substances held by the water in solution.

« ՆախորդըՇարունակել »