NOTES AND NOTICES.

Improved Marine Engines,-A fine new iron steam boat, the property of Lord F. Egerton, or in other words of the Bridgewater Trust, was recently launched from the yard of Messrs. Page and Grantham. She was named the Alice, after Lord Francis Egerton's eldest daughter, is about 170 tons burden, old measurement, is neatly fitted up, and is a handsome lively looking boat on the water. With the whole of her

machinery, fuel, &c. on board, her draft of water is only four feet six inches. She has two engines of thirty horse power each, made by Messrs. Devonport and Grinrod, of the Caledonian Foundry in this town, upon a novel and improved construction, their peculiarity consists in the fixing of the cylinders on an angle of 45 degrees, in the form of a rectangle, with the hypothenuze at the base, so that they act as a stay and support to each other. No side levers are required or counter balances; and the working parts being fewer than in ordinary engines, they are less liable to derangement, and not so much exposed to wear and tear. These engines, are exceedingly compact and have realized all that was contemplated by the ingenious makersample power-ease in working, and great strength, combined with unusual lightness. At twelve on Saturday night several gentlemen proceeded in the vessel from the Clarence Dock on a short experimental trip on the river. New engines are neces sarily stiff, and it requires some time to ascertain their proper adjustment. With all disadvantages, however, the Al ce performed their work admirably, from the moment she left the dock. A very short trip only was intended on the first occasion; but the speed of the vessel was so satisfactory, and the gratification of all on board consequently so great, that she proceeded up the river a distance of 12 or 14 miles and back -accomplishing the trip "out and home" in about two hours. On her way up she beat several very powerful steamers, and on coming down successively headed two of the Runnora packets in gallant style. The strokes of the engine averaged thirty-two per minute, but when at her full power they will make thirty-five.-Liverpool Standard, Dec. 21.

The Thames Tunnel.-This work is now, it is said, carried on at the rate of eight feet per week. It is now advanced to within about 120 feet of the wharf wall on the Wapping side of the river.

Construction of Davy Lamps.-The communi. cation from our intelligent correspondent, "Black Diamond," has excited the attention of mining engineers. Mr. Lionel Brough, of Neath, has addressed the following letter to the Mining Journal in reference thereto :-"I have had frequent occasion to point out to colliers the imperfection mentioned in the letter above alluded to, and only a few

days since it became my duty to inspect a work-a portion of which was full of' fire,' and not having any of my own lamps with me, I was induced to examine the one placed in my hands, and on unscrewing the gauze cylinder, and looking end-ways at its immediate connexion with the brass ring attaching it to the lamp, I there detected openings sufficiently large to allow of small shot being dropped through. This was a new lamp-and many others then examined were equally unsafe; I, therefore, as a temporary precaution, stopped up such orifices with clay, so as to enable me to perform the requisite services, and I have no hesitation in stating my firm conviction, that had I not done so, this lamp would have fired-that portion of the mine then under investigation being filled with an explosive atmosphere. Would it not be, Mr. Editor, most desirable that all lamps should be submitted to a strict examination by competent judges before they leave the workshop of the manufacturer? This is a subject where legislative enactment would, beyond all doubt, produce beneficial results; and it becomes the duty of all who are connected with mining pursuits to bring their knowledge and experience before the public, as I am quite convinced that the real' safety' lamp of the great and talented inventor is positively what its name infers-that is, the means of safety when well and honestly manufactured, and placed in the hands of steady men accustomed to its use-in fact, nearly all investigations, both legal and otherwise, have proved that the innumerable frightful accidents that have occurred within the last twenty years have arisen from imperfection in the fabrication of the lamp, or from shameless carelessness in its use."

Edinburgh Exhibition of Arts, &c.—The exhibition in the Assembly Rooms, which was opened on Tuesday, attracts great attention, and is crowded by all ranks of society; among whom we have noticed the Duke and Duchess of Argyll, the Marquis of Lorn, Lord Altremont, Sir Thomas Dick Lander, Colonel Douglas and the officers of the 78th Highlanders, the Rev. Mr. Bennie, President of the School of Arts. The practical illustrations are in full operation, and include a magnificent display of the application of science to art on a scale such as has never been previously witnessed in this country. The light-house reflectors and lenses, including the lime ball reflector, the reflector with coloured light, and the revolving lenses, occupy the east end of the large room, and shed a flood of the most brilliant light upon the spectator. The printing, copperplate, and lithographic presses are continually in action; and the jacquard loom, the weaving of stockings, turning of wood, modelling in clay, basket-making, paper-making, &c., present a series of processes of extreme interest to all; while the magnificent illustrations of the Polariscope, on which alone the committee have expended upwards of 501., present to the man of science a treat which has not hitherto been accessible to him in this part of the island. The experimental ar. rangements of the Polariscope are under the superintendence of Mr. E. M. Clarke, who has arrived from London at the invitation of the committee, for this purpose. It will give some idea of the magnitude of the arrangements made for this exhibition, when we state that the value of the insurance of the various models and specimens is between forty and fifty thousand pounds. We have much pleasure in adding, that the pupils of numerous schools and academies have already visited the exhibition, and on Saturday morning (this day), we understand that upwards of 800 boys, from different charity schools, are to be admitted gratuitously.-Edinburgh Chronicle, Dec. 28.

242

DESCRIPTION OF A PLAN FOR DESCENDING AND ASCENDING MINES. -BY E. O. TREGELLES, C.E. [From the Sixth Report of the Cornwall Polytechnic Society.]

Figs. 1, 2, and 3, (pp. 243, 4) are a longitudinal section, a cross section, and plan of the machinery for facilitating the descent and ascent of miners, being a modification of the plan adopted in some deep mines of the Harz, in Germany.* The machinery about to be described, is adapted for a mine 200 fathoms deep.

a a are two rods of fir, which are proposed to be made each of two pieces of Norway timber, nine inches square, scarfed together, so as to form a piece 16 inches by 9 inches. Brackets or footboards, bb, &c., are fixed to each rod, at every 10 feet, and a rod c, 24 inches square, is fixed at the outer angle of the footboard, being continuous with the rods for the whole proposed depth.

d is a ladder of ordinary kind, fixed so as to be nearly flush with the front of the footboards.

ee are staples of wrought iron, fixed to the rods a a, as hold-fasts for the men's hands, and being long, they are adapted for tall men or for boys.

fff are rollers with flanches as guides to the rods; of these a set should be fixed at every 30 feet.

g is a landing place, of which there should be one at every 10 fathoms.

hh, rods to connect the rods a a with the beams i i.

j, a strap to connect the beams together.

k, sweep rod, connecting the beams ii, with the crank . This crank is 5 feet between centres, giving to the beams a 10 feet stroke, and is worked by the engine m, shown only in the plan.

It will be obvious that if the crank d, makes 5 revolutions per minute, it will raise and lower each of the rods a 5 times per minute, so that at each change of stroke a short interval of time will occur,

*The machinery of the Harz mines to which we had reference, is constructed on the reciprocating principle; their rods are much slighter than the size we suggest, and the stroke is only 4 feet 8 inches, requiring the men to change more frequent. ly than in the arrangement proposed for the Cornish mines; as we apprehend that the risk will be diminished by reducing the number of times that the men are required to change from one rod to another; the guide rollers on the German plan, are placed at the back and front of the rods alternately; we propose having them at the sides, but this is an arrangement that may be varied at discretion.

during which the brackets b are nearly level with each other. This interval will afford sufficient time for a man to step on to the bracket that was descending, during the time when the bracket from which he steps was ascending, then at the change of stroke, he will be raised 10 feet; and stepping to each alternate rod as they stop, he will be raised a height of 200 fathoms in 12 minutes, without fatigue.

The rod c is for the person to rest against, to increase the sense of security.

At every landing place the brackets b, and staples e, would be fixed on the opposite side of the rods a a, so that if by any accident the men fall away, they would have no further to fall, than if the accident occurred whilst mounting by a ladder in the ordinary manner.

It might be desirable to introduce the shieve and band, described in page 44 of the Society's "Second Annual Report," as a security in case the rods should break: besides this, strong catches should be firmly attached by bolts to the rods a, at every ten fathoms.

The weight of each rod is about 30 tons, independent of moisture, the one balancing the other; if 40 men be ascending at the same time, the load on the alternate rods will be 3 tons, moving 100 feet per minute,=672,000 lbs. raised 1 foot high per minute, the power of 20 horses; but the friction of the rods, and machinery must be added, so that the power required is a 30-inch engine, working at 8 pounds per square inch, a 6 feet stroke, and 16 strokes per minute. A smaller engine would be sufficient if fewer men were raised at one time.

The cost of executing the whole of the work, including the rods, the machinery for working them, and the engine, may be estimated at 2,3657.

A less costly modification of machinery for the same purpose is shown by fig. 4, (front page.)

a a, are the rods as before described; bb, the brackets; cc, the rods for the men to lean against; d, the ladder; e e, the staples; ff, the rollers; g, the landing place; h h, the links to allow of the vibration of the rods ii; jj, levers to reduce the oblique strain, on the tops of the rods a a; k, is a T beam; 1, is a sweep rod, connecting it with the crank m; nn, are two elliptic wheels connected with the fly wheel of the engine; p, is the masonry,to hold down thewood framing,q.