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HUNTER'S STONE-PLANING MACHINE.

edge, and are thus made:-An inch bar of fine Swedish or English steel is forged out into plates seven inches long, one inch broad, and one-sixth of an inch thick. Similar bars of fine, soft iron are prepared in the same manner. These are smeared with a paste of borax dis solved in water, and laid in piles of twelve-nine of steel to three of iron, or three to one, alternately: each pile is wrapped round with rag thickly plastered with mud made of a loamy earth; then heated, welded, and drawn out to a bar one inch and one-eighth broad, and one-third of an inch thick: this is bent zig-zag three or four times: is again welded and drawn out to half an inch thick; and, during the heat, borax is fre quently dropped on the metal while in the fire. Two of these bars are next welded into one, and, when about twelve or fourteen inches long, it is bent into the form of a loop or staple; in the middle of this a piece of fine-grained file is inserted, of the same width, and nearly as thick all is then welded together, and the blade is formed.

Tempering. An earthen pot, twelve inches wide and six deep, is notched on the edges (the notches being opposite each other) with a file, about a quarter of an inch deep, and is then filled nearly up to the notches with water, and oil is then poured on the surface. The blade, being heated equally to a light red, is removed from the fire, and the point, entered into the notch on one edge, is passed to the opposite one, keeping the edge from a quarter to half an inch in the oil it is drawn backwards and forwards rather slowly till the hissing ceases, and the rest of the blade above the fluid has become black; a jug of water without oil is then poured along the blade from heel to point. In order to take out, the warp produced by tempering, the blade, when nearly cold, is passed over the fire three or four times; then being brought to the anvil, is set straight by striking it regularly, but moderately, with a hammer; by this means a Damascus-carved blade may be brought nearly straight. Blades made this way, in my brother's presence, when he was President of the Regency in Catch, were proved, previous to grinding, by striking at stones, ramrods, musket-barrels, and even wheel-res, without injury to the edge.- Trans. Soc. of Arts.

798

HUNTER'S STONE PLANING MACHINE.

At a late meeting of the Institution of Civil Engineers, the merits of the patent stone-planing machine formed the subject of conversation. Drawings of the machine, and several specimens of the planed stone, being laid upon the table, Mr. Lindsay Carnegie explained its mode of operation, and made several statements as to its actual performances. The>> principal objection to all former mas chines for a similar purpose-the im mense friction and consequent destruction of tools-seems to have been completely obviated in this instance, as Mr. Carnegie stated, that " the wear of tools was so trifling, that it was scarcely worth noticing in calculating the expense of working the machine:" this arose, he, said, from the peculiar mode of working, -the tool not coming in contact with the stone more than four times in a foot, and: thus not being heated by friction, it does not lose its original tempering.

At a subsequent meeting of the Institu tion, the subject was resumed, when Mr. Cubitt, the eminent engineer, said he had occasion to be in Scotland a short time since, and having heard much of Mr. Lindsay Carnegie's machine and its operations, he sent three slabs of stone -two slabs of very hard slate stone, and one slab of hard Yorkshire-that he might see them planed in order to speak to its effect. These slabs were each three feet long and fourteen inches wide. They were put upon the planing machine, and the roughing tool passed over each of them in three minutes, and the smoothing tool in four minutes; it planed them very well. His opinion of Mr. Lindsay Carnegie's machine was decidedly favourable. He thought it not particularly useful in dressing stone for building purposes, but more adapted for slates, pavements, and landings, which it planes admirably. He thought all slab work might be planed by it at a farthing, or from that to a halfpenny, per square foot.

The immense saving which will be effected by the use of this machine in Lon don may be imagined from a statement made by a member, that he had just be fore been charged ninepence per foot for smoothing a stone seven feet by four and a half. According to Mr. Cubitt's statement, the maximum cost by the machine would have been one halfpenny!

80

NOTES AND NOTICES.

We understand that a working model of the machine has been placed in the Adelaide Gallery for the purpose of exemplifying its mode of workingwhich it does as well as can be expected, when it is considered that the moving part of the model does not weigh above a hundred weight, while the same part in the machine itself weighs about two tons. From this model, however, in connexion with the description given in our 636th Number, any person interested may fully understand the whole modus operandi of this important invention.

NOTES AND NOTICES.

Economy in Linen-Washing.-A correspondent of a Dundee paper writes as follows:-" After many experiments made by myself and others, I find that a little pipe-clay dissolved among the water employed in washing, gives the dirtiest linen the appearance of having been bleached, and cleans it thoroughly with about one-half of the labour, and fully a saving of one-fourth of soap. The method adopted was, to dissolve a little of the pipeclay among the warm water in the washing tub, or to rub a little of it together with the soap on the articles to be washed. This process was repeated as often as required until the articles to be washed were made thoroughly clean. All who have inade the experiment have agreed that the saving in soap and labour are great, and that the e'othes are improved in colour equally as if they were bleached. The peculiar advantage of employing this article: is, that it gives the hardest water almost the softness of rain-water.

Purification of Coal-gus.-Mr. H. Phillips, su perintending engineer of the Exeter Gas works, has discovered the means of arresting the volatile alkali, to which, from its known corrosive property, when in contact with copper or brass, is to be attributed the destruction of cocks, fittings, and meters; and as azete (one of the constituents of ammonia) is highly injurious to respiration, that peculiarly pungent and obnoxious quality of the air in rooms in which gas is burnt for a long portion of the night, is probably augmented, if not produced by it, from the circumstance of the amimonia not being previously separated: azote is alike injurious to combustion;-by employing two burners of the same size, and supplying one with gas from which the ammonia has been removed, and the other with gas from which the ammonia has not been removed the superiority of the light produced by the one over that produced by the other will be clearly apparent, Mr. Philips has taken ont a patent for his discovery.-Worcester Journal.

Preserving Paste.-Paste made by putting acetate, or sugar of lead, into it, instead of the old way of mixing it with alum, keeps it from monlding, and quite moist for months together.-New Monthly Magazine.

New Lamp.-A lamp of a new construction, which describes a circle of light of about thirty feet in diameter of the apparent intensity of sunshine, showing the objects within its sphere as distinctly as those on the table of a camera obscura, has been erected at the head of the inclined plane in St. Leonard's depôt. Its object is to enable the engine-men to have a distinct view of the inclined Topes during the night, and this has been fully at

tained. The lamp consists of an argand burner placed in the focus of a large speculum of a pecu. liar form, by which the whole light is distributed just on the space where it is required; it is computed that the light on the above space is equal to that of twenty-five or thirty similar burners in common lamps. A lamp of this kind we have no doubt would be useful for other purposes: it appears to us that the largest assembly room might be brilliantly lighted by one placed at each end of the room, and one would be sufficient to light the stage of a theatre. The cost of this one is said to be about 2007., but we understand it saves an annual expense of about half that sum. The inventor is a Mr. Rankin, and he names it the Conoidal lamp -probably because the light is thrown from it in the form of a cone.-Caledonian Mercury.

New Liquor-Gauge.-A gauge, upon a very simple and excellent principle, which has just been introduced in the new gin palaces, has been invented by Mr. Fage, the hydrometer manufacturer, to show the quantity of liquor, in inches, contained in a cask or vat at any time. The gauge is a vertical glass tube of the same altitude as the cask or vat, and about the size of a large barometer tube, open at both ends. The lower end is securely let into a brass tube about six inches long, at right angles, with a valve, or stop-cock; this tube is fixed into the lower part of the side of the cask, as near the bottom as can be, similar to a cock. The glass tube is attached to a brass index about two inches wide, and of the same height as the glass tube, which is divided into inches; and the number of inches is engraved in figures, reading from the bottom to the top. It is evident, when the valve at the foot of the glass tube is open, the liquor in the vat or cask will rise to the same height in the tube asit is in the vat; and, by means of the br ss index, that it will show the number of inches of liquor in depth there are in the vat or cask. It saves considerable labour and trouble to the Excise officers; as, by calculating the quantity there is in each inch in depth in the cask when the gauge is first tixed, they can make their entries without the trouble of the gauging-rule.-Architectural Mag.

Communications received from Mr Mackintosh -Mr. Elliott-Iver M'Iver-G. P.-A Constant Reader- Mathematicus-W. W. G.-Mr. Barrett.

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The Supplement to Vol. XXIV., containing Title, Contents, Index, &c., and embellished with a Portrait of Mr. Walter Hancock, C. E., is now published, price 6d. Also the Volume complete in boards, rice 9s. 6d.

Patents taken out with economy and despatch; Specifications, Disclaimers, and Ameudments, prepared or revised; Caveats entered; and generally every Branch of Patent Business promptly transacted. Drawings of Machinery also executed by skilful assistants, on the shortest notice.

LONDON: Published by J. CUNNINGHAM, at
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Mechanics' Magazine,

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82

REPORT OF EXPERIMENTS ON THE EXPLOSIONS OF STEAM-BOILERS.

REPORT OF EXPERIMENTS MADE BY THE
COMMITTEE OF THE FRANKLIN INSTI-
TUTE OF PENNSYLVANIA ON THE EX-
PLOSIONS OF STEAM-BOILERS, AT THE
REQUEST OF THE TREASURY DEPART
MENT OF THE UNITED STATES.
(From the Journal of the Franklin Institute.)

The Committee of the Franklin Institute on the Explosions of Steam-Boilers, respectfully present to the Secretary of the Treasury, their Report of the experiments undertaken at the request of the department. The queries which were submitted by the Committee to the officer at whose request the experiments were instituted,* have formed the basis of the labours of the Committee. They have, however, availed themselves of the privilege accorded, of trying such other experiments as might grow out of the investigation, or as they might deem of special interest.

The object of the experiments was to test the truth or falsity of the various causes assigned for the explosions of steam-boilers, with a view to the remedies either proposed, or which may be consequent upon the result of the investigation. The causes being accurately known, the attention of ingenious men is led away from false suppositions, which can only waste their time and talent, if taken as the basis of their plans for safety; greater hope is afforded of an efficient remedy; ap. plications of an indirect, or it may be of a positively injurious sort are avoided; and if the causes be found to be such as, for the present, to baffle ingenuity in their removal, the attention is directed more fixedly towards the means of protection against the effects of such accidents. The Committee hope that the results of their inquiries will not be found without fruit.

It was the aim of the Committee to provide for the experiments an apparatus of such dimensions as to furnish results applicable to practice, without being so great as to be managed with difficulty, or to increase, unnecessarily, the danger incident to parts of the investigation. To arrange the apparatus and complete the details, they secured the services of an able and experienced mechanic, David H. Mason, by whom, or under whose direction, the nicer parts of the work were executed, and who assisted, also, in the experiments.

The Committee propose, first, to give a general description of the apparatus used, followed by details in the more complex parts; next, to report the results of their examination upon each of the questions proposed for investigation.

The Hon. S. D. Ingham, late Secretary of the Treasury of the United States.

General Description of the Apparatus.

The boiler used by the Committee, and represented in figs. 1, 2, and 3,* was twelve inches in interior diameter, two feet ten and a quarter inches in length within, and onefourth of an inch thick; of rolled iron, with the heads rivetted in the usual manner. Fig. 1 is a side-view, and 2 and 3 are endviews of the boiler, and of the apparatus connected therewith. The boiler was placed horizontally in a furnace, the fire surface extending about half way round the cylinder.

The

The furnace was arranged for a charcoal fire, the grate-bars extending the whole length of the boiler, and the fire being applied through nearly the whole length. draught entered by an opening, closed in the usual manner, and left the furnace through a flue placed at one end and side of the boiler. It will be convenient to use the terms fireend or front of the boiler, in reference to the proximity to the furnace-door, and back-end of the boiler, In fig. 2, A is the ash-pit door, B the furnace-door; and in 1 and 3, C is the furnace-chimney.

In order to examine, readily, the interior of the boiler during the progress of the experiments, each head was provided with a glass window (D, figs. 2 and 3). The glass used was three-eighths of an inch thick. The openings in the ends, which were rectangular, were two and a half by one and three quarter inches wide. At first a glass plate, rather larger than the rectangle just mentioned, was applied to the opening, and kept in its place by four strips of brass secured to the heads, on which a rectangular frame, having the surface next to the glass accurately ground, was secured; the pressure of the steam keeping the glass against this frame, closed the boiler. Fractures occurring frequently from the rapidly varying, and often considerable, pressures within the boiler, and taking place by pressing the middle part outwards, as was proved by examin ing the fractures, frames with cross bars, see figs. 2 and 3, having the interior surface carefully ground, were used. The difficulty of properly adapting the surface of these frames to the glass having been removed, they were used in the later experiments, and were found to afford a sufficiently good view of the interior of the boiler, notwithstanding the obstruction by the cross bars.

Three gauge cocks were placed in the front head of the boiler; their positions will be particularly stated hereafter; they are shown in figs. 1 and 2, at a, b. and c.

To the same head, and by the side of the gauge-cocks, a glass water-gauge (», x, figs.

The end-views will be given in our succeeding Number-.

REPORT OF EXPERIMENTS ON THE EXPLOSIONS OF STEAM-BOILERS. 83

Fig. 4.

1 and 2) was attached, a particular description of which will be given in the detail of experiments made to compare its performance with that of the gauge-cocks.

To supply the boiler with water, a foreingpump EE' FG, figs. 1 and 3, was placed near the back-end. This pump was of the ordinary construction, with a solid plunger and conical valves; the diameter of the pump was one inch, and the play of the piston one inch and three quarters. The diameter of the pipe FG, by which the water was conveyed from the pump to the boiler, was three hundredths of an inch. By a couplingscrew this pipe could be connected with either of the stop-cocks d e, fig. 3, in the back-end of the boiler: the opening of these cocks was two hundredths of an inch in diameter.

To ascertain the elasticity of the steam within the boiler, a closed steam-gauge (H, figs. I and 3) was used, a particular description of the construction, &c. of which will be given. This instrument was placed upon the same stand (1, figs. 1 and 3) which supported the pump, so that the same experimenter could observe its indications and attend to the working of the pump. The eistern of the gauge was connected by a flexible pipe fg with the upper part of the boiler.

The safety-valve is shown on the top of the boiler (K, fig. 1), midway between the heads. The graduation of it required much pains, and will receive a separate discussion.

Near the safety-valve is represented at L, figs. 1 and 3, the fusible plate apparatus, consisting of a sliding-plate of iron, moved by a lever. On the other side of the safetyvalve are the thermometers M and N, fig. 1, plunged into iron tubes to give the temperature of the steam and water within the boiler.

Above this appears the reservoir O, containing the water intended to maintain the seales of the thermometers at a constant temperature. All these parts require a more detailed description,

DETAILS OF THE APPARATUS.

Of the Steam-Gauge.

The steam-gauge consisted of a glass tube closed at the upper, and open at the lower end, which passed steam-tight into a reservoir for mercury: when this reservoir was connected with the boiler, the pressure of the steam raised the mercury into the gaugetube, compressing the air which the tube contained. The first mercurial-gauge which was made was broken by a sudden access of surcharged steam, in the experiments upon that subject, and was replaced by a second one. The method of graduation, and, in general, the description of the second gauge, will serve also for the first; the details, only, varied slightly.

The glass gauge-tube was 26'48 inches in length. To the lower end was connected an iron ferule, terminated above by a projecting ring. This ring was pressed upon the upper end of the pipe h, fig. 1, by a coupling-serew, which served to form a tight juncture between the gauge and the cistern. The cistern i was a cylindrical vessel of cast-iron, having the two projecting tubes h and k, upon which screws were eut; the first of them has been alluded to as giving a passage to the glass tube of the gauge; the second was coupled by the pipe fg, figs. 1 and 3, to the boiler.

The gauge-tube was not of precisely equal diameter throughout, and it was judged more accurate to graduate small portions of it into equal volumes. This was done by intro

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