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The forms of lava are few. It is generally | Tarpeian rock and of the Aventine and Celian hills amorphous that is, without any particular form- are composed of this rock, which was used by the but occasionally modern lava, like basalt,

a primitive outline.

assumes Romans for building purposes.

Granular tuff is very different in external apVery curious changes take place in lavas which, pearance from stone tuff. It is of a blackish-brown like those surrounding the crater of Solfatara, are or yellowish-brown color, and of a much more exposed to the action of decomposing vapors. earthy character. It sometimes assumes a clayThey are frequently reduced to the state of powder, like aspect, and in this form is used for making and their color becomes quite white. The follow- bricks and earthenware. The Pincian, Quirinal, ing varieties are mentioned as occurring in Solfa- Viminal, and Esquiline hills, and the greater part tara. 1. A light lava, having the color of blue of the Celian and Aventine, are composed of a baked brick, of a coarse, earthy grain, and argil- peculiarly friable variety of granular tuff.

laceous odor. 2. Of a cinereous color, containing iron pyrites. 3. An extremely white lava, almost reduced to powder, containing pyrites in layers. 4. A heavy lava, lava, of a livid gray, abounding in pyritic crystals. 5. A lava white on the surface and reddish blue in the interior.

With the exception of Vesuvius, the greater part of the Phlegræan fields are composed of tufaceous rock. Naples is founded on tufa, and that rock is used as material for its buildings. The surrounding plain is tufa, and the hills to the north and west. The craters of the lakes Agnano and A peculiar kind of rock, known in Italy as Averno, parts of Solfatara, Monte Nuovo, the breccia, is sometimes found in the neighborhood of promontory of Misenum, and the island of Bocida, volcanoes. It consists of angular fragments of dif- are of this material. Herculaneum was destroyed ferent kinds of lava cemented together. It is often by a tufaceous torrent. Tufas are sometimes of various and very beautiful colors. The follow- formed almost entirely of pumice, and not unfreing kind is found in large isolated masses on the quently contain organic matter. The sand and island of Lipari; its principal substance is an ashes which are thrown out in such enormous earthy lava of a bluish gray, coarse grain, and quantities during volcanic eruptions, may be classed little hardness. It contains-1, lavas of a black under tufaceous rock. The fragments of which and gray color; 2, a vitreous lava of a beautiful they are composed frequently become bound tocolor, between green and blue, resembling pitchstone; 3, numerous small pieces of a cinereous, compact pumice; 4, pieces of whitish, semi-transparent glass; 5, small pieces of a colored glass, resembling fictitious glass.

The number of minerals which are found in small quantities embedded in the lavas of Vesuvius is very numerous. Garnets occur frequently in some of its lavas.

Scoriæ, so called from their analogy to cinders. are found in masses of small diameter, of a very rough exterior and porous structure, as if they had been pervaded by gas. In other respects they resemble lava, and they are, no doubt, portions of heated lava broken off from the general mass, either before it issues from the crater, or whilst it is cooling.

Scoriæ sometimes assume a pear-like shape, when they obtain, in Italy, the name of bombes, or tears. At other times they have the appearance of twisted cables, trunks of trees, icicles, and other objects. They are found in Stromboli interspersed with beautiful colored crystals; some of the crystals being of a fine grass-green, others of an emerald color, and some a mixture of green and yellow.

When acted on by decomposing vapors, they undergo similar changes to lava; they lose their color, become encrusted with sulphureous matter, and are rendered so soft that they may be cut with a knife. Pumice is supposed to be the scoriæ of the glassy lava called obsidian. It occurs abundantly on the Lipari islands and in the Santorian archipelago.

Tufa is a name given by the Italians to a rock, generally of an earthy texture, composed of an agglutination of scoriæ and other loose products of volcanoes. It occurs abundantly (the product, of course, of extinct activity) in the neighborhood of Rome, where two varieties-known as stone and granular tuffs are found. Stone tuff is of a reddish-brown color, with orange streaks. It occurs in beds from one to six feet thick, intersected by vertical or sloping clefts. The summits of the

gether after their fall.

All lavas contain iron, distributed in small quantities throughout its mass. Occasionally this iron appears to be expelled, and is found crystallized in vertical plates. The most remarkable example of this process is in Stromboli. When examined closely the plates are seen not to be plane surfaces, but to have a polygonal form. The faces of the polygons are of different sizes. The largest exceed four inches in length, and three and a half in breadth. They have the brilliancy and polish of the finest steel, and reflect the light like the most perfect mirror. In a similar manner, globules of iron are sometimes found adhering to the external surface of lava. In the island of Ischia, and in other places, a ferruginous sand is found, in which the iron has a crystalline form. It occurs most abundantly by the sea-shore, and probably proceeds from the gradual wearing down of lava. Volcanoes sometimes eject masses of rock which do not appear to have undergone fusion-at least, recently. Thus Jorullo threw out fragments of granite; granular limestone is found in Somma.

Having mentioned the external forms of volcanic products, it remains to mention their internal structure.

The minerals felspar and augite (the latter being probably identical in chemical composition with hornblende) compose the greater part of the igneous rocks of all ages. Modern lavas have been classified as trachyte, greystone and basalt, according as one or other of these two minerals predominates in them. In the trachytic lavas, felspar is in greatest quantity. In the basaltic, augite. Greystones are an intermediate class, which contain the two minerals in about equal proportions.

Though volcanoes acquaint us with many new combinations of minerals, they have not added to the number of elementary substances. When reduced to their ultimate constituents, volcanic rocks are found to consist of the same matter as stratified rock. The following are the chemical analyses of felspar and augite :

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six acres, in the waste of the nine-foot seam of

52.0 coal.
3.3

10.0

10:00

Of these minerals, therefore, silex constitutes more than half the weight. The analysis of the compound rocks shows that, in passing from the trachytic to the basaltic kind, the quantity of silica gradually diminishes. We give below the analysis of obsidian, (a trachytic lava,) of a greystone lava,

and of basalt :

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It is supposed to have been set fire to by some per13-2 sons who had been distilling illicit whisky in it. Shortly after its discovery it rapidly extended 16-7 itself, and threatened the destruction of the entire 4.8 coal-field. A sum of £16,000 was laid out in surrounding the fire with a puddle-wall, to prevent its extending to other workings. The wall took five years in building, the workmen being frequently driven back, and obliged to recommence at a greater distance from the fire. It was, however, finally completed nineteen years ago. In the building of this wall the lives of nine men and three women were unfortunately lost at various times by the roof falling down and cutting off their retreat, and the fire overwhelming them before they could be excavated. One unfortunate girl was enclosed in this manner and not burnt, but roasted to death, so that, to use the expression of those who found her, when they took hold of her 2-25 arm to lift her it came off like the wing of a 2.60 roasted fowl. The fire having taken place near 20 the crop of the coal it was surrounded by running the wall from the crop in a form resembling nearly a semicircle towards the dip, and then round again towards the crop, so that the line of the crop formed the diameter of the circle.

Basalt.

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44.50

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(1.0

14

1.

99.

97.6

16-75

9.50

0

2.

97-72

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Still, however, the wall required constant attention; as, if the fire once passed it, it would be a matter of great difficulty and expense again to surround it. In consequence it has cost the owner of the property (the Earl of Mausfield) about £200 a year in keeping it up, and in the payment of overlookers, there being always a danger of the fire 77-5 getting, by some accident, such as a fall of the 17.5 reof, beyond the wall into the lower wastes, and 3.0 burning the extensive coal field below. Vari

1.7

99.7

It thus appears that, taking equal weights of granite and pumice, they give nearly the same chemical constituents. A striking resemblance is

also perceived between the constitution of modern

lavas generally and that of granite. Trachytic

and basaltic lavas of ancient date are found, in

some cases, to have penetrated granitic rocks, and in those cases must have originated below the granite. The date of these lavas, which are the earliest of which we have cognizance, is assigned as that of the appearance of the earliest tertiary rocks. But we must not extend these observations further, nor should we have extended them so far, had we not found that it was scarcely possible to give completeness to our sketch of this comprehensive and interesting theme within narrower limits.

BURNING WASTE OF CLACKΜΑΝΝΑΝ.

TO THE EDITOR OF THE TIMES.

ous reports have from time to time been made by men of great authority in the coal trade, all of which have agreed in the utter impossibility of extinguishing this fire. It will, nevertheless, readily occur, that if the fire was thus, as it were, corked and bottled up to itself, it ought to have gone out from want of air. This, however, was not the case, for no part of the fire mine being deeper than twenty fathoms, and some of it running at no great

distance below the surface, it obtained a sufficient

supply of air thence, as well as through the leak

ages in the puddle-wall, to maintain a smouldering,

sulky, and volcano-like existence--sometimes more active, and sometimes less so, which could be traced by occasional falls of the surface, the last of which occurred about five months ago, laying bare the burning waste and discharging smoke and

steam.

There are about twenty-one old shafts into this fire mine, most of them partially filled. Some of them were sunk for the purpose of giving air to the workmen when building the puddle-wall, and some are old working shafts. There is also a drift running in a slanting direction from the crop, which was a clear passage for about sixty yards, and was then partially stopped by falls of the roof, but through which there was sufficient opening for air to pass into the mine. This drift served for an upcast. Near to the wall was a shaft, at the opposite side of the burning waste, which, in this experiment, served as a downcast into the waste.

SIR-The public will, I feel sure, be deeply interested in an experiment on a gigantic scale which has just been brought to a satisfactory conclusion under the superintendence of Mr. Goldsworthy Gurney. The object of the experiment was to extinguish a fire in the South Sauchie colliery, near Alloa, about seven miles from Stirling, which has raged for about thirty years over an area of twenty-then before them of the fact of a burning coal-mine

Lord Mansfield's attention was called by the members of the committee of the House of Lords, who sat in 1848 to consider the best means of preventing accidents in coal-mines, to the evidence

at the Astley Collieries, Lancastershire, having the space is filled, both of which principles were been extinguished by the singular process of pour- recognized and acted on during the process of cooling in choke-damp, suggested and carried out by ing, a process which Mr. Gurney considered of Mr. Gurney, a report of which, in a letter dated great importance. In conversation with him on the 30th of April, 1849, appeared in The Times of this point, previous to his leaving town, I made a the day-a fact so difficult to believe, and appar- suggestion which he was pleased to consider imently impossible, that it was not generally credited, portant, and at his request I accompanied him to except by men of science. Lord Mansfield com- the field of action, and was present during the conmunicated with Mr. Gurney, who inspected the flict with our underground antagonist. fire mine immediately after the rising of the committee of the lords, accompanied by Mr. Mather, the honorary secretary of the South Shields commission, Mr. Darlington, the proprietor of the Astley Colliery, and Mr. Jamieson, sheriff clerk of Clackmannan. After this inspection Mr. Gurney reported to Lord Mansfield that, notwithstanding the immense extent of the burning waste, he thought it possible to extinguish the fire; and, ex-in diameter and about nine feet long. The cylintraordinary as it may appear, this object has been effectually accomplished by a simple and inexpensive process.

We are accustomed to judge of great things by small, and, as a popular illustration, all the world knows practically that putting on an extinguisher puts out a candle; but perhaps few have taken the trouble to consider why it does so. It is simply that the extinguisher contains a very small quantity of air, of which about one fifth is oxygen, and the rest nitrogen. As soon as this oxygen is consumed, which in so small a quantity of air as the extinguisher will hold is almost at once, nothing remains to support combustion, and the candle goes out; for the extinguisher then contains only the nitrogen of the air and carbonic acid, the product of the combustion of the candle, which mixture of nitrogen and carbonic acid is chokedamp. It is, of course, obvious that if the fire mine could have been similarly treated it would have extinguished itself by the products of its own combustion, as in the above case of the candle, and as is often the case in coal-pits. The difficulty was that another element would come into the problem, which was, that supposing the mine to be placed under an extinguisher, (almost an impossibility, considering its size,) and all combustion to have ceased, still the magazine of heat collected during so many years' burning would continue, and cause the mine to reignite on the reädmission of the air.

Mr. Gurney's method of effecting this object was to force a stream of chokedamp through the mine, by means of the high-pressure steam jet, at such a temperature as would, after putting out the fire, cool down the mine below any degree of heat that would permit it to reïgnite on the admission of atmospheric air, and at such a pressure as to make all the leakages of the waste outwards of chokedamp, so that every inlet might become an outcast by means of which the atmosphere was perfectly excluded from all contact with the fire.

Hot and cold are comparative terms. The heat of boiling water, though much too hot for the hand to bear, is much too cold to set fire to coal. If, then, a stream of chokedamp at or below this degree of heat were passed through the mine it would gradually carry off the heat of the lately burning surfaces, a process which one may term the abstraction of heat. It also happens that when different parts of a limited space are of different degrees of heat their tendency is to equalize the temperature of the whole, and a general diffusion takes place; that is, the cool parts become hotter and the hot parts cooler; and this is effected by an internal self-circulation of the air or gas with which VOL. XXX. 3

CCCLXXII. LIVING AGE.

About the end of March Mr. Gurney, accompanied also by Mr. Mather and Mr. Jamieson, commenced operations. The machinery for conducting the experiment consisted of a high-pressure steam-boiler, about sixty feet of inch gaspipe, and a small cone for the high-pressure steam-jet at the end of it, which jet was placed at the proper striking distance from a cylinder of sheet-iron one foot

der was the passage between a coke furnace and the downcast shaft, through which the air was driven by the force of the steam-jet, and, by a simple contrivance, we were able to blow in either the air passed through the furnace, or fresh, at pleasure. Mr. Mather and Mr. Jamieson descended this shaft, accompanied by three or four workmen, Mr. Gurney blowing them in fresh air from above, and there cleared away two old iron doors into the waste, and knocked a hole through an old puddle-wall, and then, hearing a good deal of rumbling and rushing, as if the roof were falling, they thought it more prudent to retreat, as they had effected their object of opening a passage for the gases into the burning waste. They, however, had spent some time in close proximity to the fire, where Mr. Mather seemed to be quite happy and in his element; indeed, he has a particular taste for fire. He came up one of the pits one day with a hot cinder stuck in his gutta percha mining cap and half melted through it. The heat at the bottom of this shaft was 100° at this time. These obstacles having been cleared away and a free passage obtained, the shaft was covered with iron plates and clayed over, so as to render it air-tight, and the chokedamp was turned on. That extinguishing gas was made by passing the atmospheric air through an intense coke fire in a brick furnace, which deprived it of all its oxygen, or rather the oxygen combined with the carbon of the coke, and formed carbonic acid, which gas, in mixture with the nitrogen left, was forced through the furnace, along the iron cylinder, down the shaft, and into the burning waste; the quantity of coke consumed being a sufficiently accurate measure of the quantity of air passed.

After blowing in about 8,000,000 of cubic feet: of chokedamp, (at the rate of about 7,000 cubic feet per minute,) which we calculated to be about the contents of the waste, (allowance having been made for falls of the roof,) we found the upcast or high level shaft or drift was full of it to the mouth,. flowed over, and ran along the ground, extinguish-ing lights if held near the surface of the earth at some distance from the spot. We found when we ceased blowing in gas that after a time the chokedamp receded in the upcast, and that when-ever we blew it into the downcast it poured out of the upcast in volumes, being thus a perfect measure of the quantity of chokedamp in the mine, and giving us a proof that it had passed completely through it.

After keeping the mine full for upwards of three weeks, it was thought advisable to blow in chokedamp at a lower temperature than we had been

previously doing, which we believed to have been about the temperature of 250, though we did not test it very accurately. In order to effect this Mr. Gurney used a very beautiful contrivance, by which, by the power of the steam-jet, water was driven into the shaft along with the chokedamp in the form of the finest spray. Indeed, the best idea that is to be given of it is that it resembled Scotch mist, a medium universally admitted to have very rapid and powerful cooling properties. This process Mr. Gurney thought very important, as he considered the difficulty of cooling the immense magazine of heat after the fire was extinguished, to prevent reïgnition on the admission of fresh air, to be the most uncertain part of the whole experiment. That he could extinguish the fire he had no doubt whatever, but to cool down the waste against the existing conditions of non-conduction and non-radia'tion, he considered far more difficult.

The water being so minutely divided by the immense force of the jet, was held in suspension in the air, and floated on with it through the water. A large portion was in actual solution, but far the greater part was simply mechanically suspended like fine mist, and did not precipitate or condense. When the temperature was sufficiently reduced, as indicated by the thermometer, so as to leave no fear of reïgnition, fresh air was blown in by the spray-jet, so as to pass through the mine charged with water, in order to cool it enough to allow of its being entered. After a time the action of the jet was reversed, and the air drawn through the mine in a contrary direction, so drawing out the air we had blown in charged with mist, and we continued drawing out mist or vapor for several days, which showed that it had filled every part of the waste, and had remained suspended. The temperature of the air that was drawn out gradually decreased at the rate of about six degrees a day. After about one month's operations the downcast shaft was uncovered and descended, and found to be of a temperature of about 98. The waste was examined by Mr. Mather, who had reported that falls had taken place so as to leave no passage to enable us to go any distance into it. A shaft was then sunk into the middle of the burning waste at the point where the fire was supposed to have been most fierce at the commencement of our operations. The roof was here found to have fallen, so that it was impossible to enter. The fire, however, was extinct. Several bore-holes have been driven into the waste at different points, and no fire can be discovered; and this mighty volcano is extinct. The vast amount of property endangered, (in this case of the value of near £200,000,) and the frequency of the occurrence of these kinds of accidents, give a great public interest to this operation. It is but two years ago that the proprietor of the Dalquarren coal-mine in Ayrshire, lost in half an hour £1,200 a year by a fire breaking out in one of his pits, which led to the total abandonment of the seam in which it occurred. It has burnt and destroyed the wood on the surface, and extended over fourteen acres, but is now, I may add, undergoing extinction by the same process, with every prospect of success. The great importance of the subject, in connection with the commercial and mining wealth of the country, must be my excuse for trespassing thus much on your columns and on the public patience.

I remain, sir, your obedient servant,
EDWARD CAYLEY.

9, Manchester Buildings, Westminster, May 1.

From the Morning Chronicle, 17th May.

THE UNITED STATES IN THE EXHIBITION. THE number of articles sent from the United States to the Exhibition is neither what was expected of them, nor, we believe, does it adequately represent their capabilities. There are, nevertheless, many things in their collection which may be examined with interest and profit, and which do credit to their industry, ingenuity, and skill.

Foremost among the articles displayed in this division of the Exhibition are a coach, three or four wagons, a "buggy," technically so called, and a trotting "sulky." We call these "foremost," because, both by the prominent place they occupy, and on account of the real merit of the vehicles themselves, they are really so. The coach-styled by the exhibitor a "carriola" is a very creditable piece of workmanship. It is of good design. apparently most thoroughly well built, and finished with great regard to good taste. There is nothing of the gewgaw style about it. The color, decorations, mountings, finish, and ornaments are all rich and neat. It sweeps gracefully over its curve, as a coach ought to sweep. The carvings upon it are admirably well executed, and, for symmetry and good keeping in every part. from the step of the footman to the board of the driver, it deserves high commendation. The wheels are much lighter than in carriages of a similar kind in England. This is claimed as a decided improvement. Certainly the appearance of the vehicle is improved by the absence of that bulkiness which gives a lumbering aspect to many an English carriage; and, if the roads of our transallantic brethren are not too rough to deal fairly with such wheels, we know not why they should be considered unsafe upon English turnpikes.

The other vehicles exhibited are respectively entitled a York wagon, a Prince Albert wagon, a slide-top buggy, and a trotting sulky. The chief characteristic of all of these is their extreme lightness of weight, when compared with their size. They are richly finished within and without, and beautifully carved; they are upholstered with exceeding taste, made with constant regard to the comfort of the rider, and exhibit very considerable artistic merit in their design. The wheels are made from carefully chosen material, the joints exactly fitted, the felloes (two in number, instead of the usual five or six, for greater strength) are confined by a steel insertion and bolts, and the axletrees are exceedingly neat and strong. It is claimed for these axletrees (an American invention) that, in loss of friction, strength, freedom from all noise in motion, and cleanliness, they are superior to any in England. Several of these lighter carriages are now in use in this country, and give great satisfaction; and several more of a similar manufacture have been recently ordered from New York. Indeed, it is not difficult to understand why they should become favorites out of London; nor how reluctantly a lover of quick driving would return to the heavier vehicles of city manufacture.

There are several sets of harness, both single and double, among the articles exhibited, which deserve notice. That exhibited by Messrs Lacey and Phillips is a rich and elegant specimen of manufacture. It is made from leather of the first quality, and with perfect thoroughness of work. The mountings are of solid silver, with ap appropriate and graceful designs. In this, as in all the other harness shown, there is remarkable lightness and airiness, and an obvious endeavor to do away with all superabundance of weight.

On a bay in the main aisle, upon the south side of the building, are two chandeliers and several lamps, from the manufactory of Messrs. Cornelius and Co., in Philadelphia. The great use of oil in the United States has led to many improvements in lamps-especially in those upon the solar principle, as it is called (where increased draught is made to bear upon the combustion) which are unknown

same purpose is uncertain. In the minds of sailors there is always an objection to fixtures above deck, which would be likely to impede their general introduction.

Together with daguerreotypes, before alluded to, there are exhibited camera obscuras by C. C. Harrison, of New York, the results of which, in the pictures that hang above them, are exceedingly

among us. Unpretending as these lamps appear, favorable. There are shawls from the Bay State it is stated that they will give an amount of light mills, of beautiful color and a high perfection of greater by one half than any others in use The manufacture; white cotton goods, which, in bleachchandeliers hanging above them are graceful speci-ing, finishing, and putting up, appear equal to mens of workmanship, designed in good taste, and Manchester products; some very beautiful flannels, showing a crystal purity of glass. The casting is single-milled doeskins and wool-back cassimeres of remarkable for its fineness, sharpness, and uniform- thorough fabric; tweeds, well mixed and of good ity. The branches, formed by arabesque scrolls, colors; a salamander safe, well made; an improved -profusely ornamented with birds and flowers, bank lock, ingenious and well executed; a patent delicately sculptured or in bold relief, with centres of richly cut glass, claim particular approval for their elegance and lightness of design. This is among the youngest branches of manufacture in the United States, it being scarcely fifteen years since every chandelier, girandole, mantel lamp, and candelabra used in that country was imported from Europe; and it argues considerable enterprise and perseverance, on the part of the manufacturers, that they have attained so much excellence as to be willing to vie in the Exhibition with the oldest and most celebrated houses of the world.

On the south side of their portion of the building, the contributors from the States exhibit, under the general classification of raw material, many very excellent specimens. There are among these a large variety of articles, such as Indian corn, ground, hulled, and in the ear; rye, oats, barley, wheat, rice, cotton, tobacco, minerals, chemicals, woods, brooms, beef, pork, lard, hams, and almost everything else identified with the productions of that country. Next in order are to be seen daguerreotypes, paintings, herbaria, and prints, with some samples of stained glass suspended from the galleries, and cottons, carpetings, wrought quilts, calicoes, and needlework, tastefully diplayed around. Considering the distance from which these had to be conveyed, not only across 3000 miles of ocean, but often from little short of that distance inland-and considering, too, that it is not in her manufactures that America makes her chief impression upon the world-we regard this portion of her exhibition with great interest. In pianofortes there is a show highly creditable to the manufacture of musical instruments in the United States. Pirson exhibits a seven-octave grand

a

paying machine for pitching the seams of vessels, the box being provided with ventrical wheel, which receives the hot melted material, and applies it neatly, economically, and directly to the seam to be covered; an air-exhausted coffin, car-wheels for rail-roads, wood and cork legs, clocks, watches, dentists' tools and works, India-rubber goods of various forms, mathematical and solar instruments, a self-determining variation compass, trunks, boots and shoes, hats, specimens of printing and binding, together with pistols, rifles, and other weapons of offence and defence. Of these rifles, manufactured by Robbins and Lawrence, it is but just to say that they are among the best, if not the best, of any rifles manufactured in the world, the Americans claiming to excel in this species of manufacture. They are made from the best selected Copake coldblast forge iron, and are of an unpretending style, but remarkable for a plain, substantial and perfect finish; they are strong, simple, and thorough in their workmanship, and eminently adapted for real service.

Two bell telegraphs, exhibited in the central avenue, very deservedly attract much attention. The bell telegraph, otherwise called an "annunciator," is an invention made to supersede the awkward array of bells, in houses and hotels. It is an extremely neat and beautiful article, and indicates whence the bell was rung, by uncovering a number corresponding to the number of the room-and this, too, for any length of time afterwards, until, by the touch of a spring, the number is recovered. In the large hotels in the United States, and in many private residences, it is much used.

In the moving machinery department, among other objects of interest from the United States, is

pianoforte; Chickering a semi-grand, and other a machine exhibited by Mr. Charles Morey, called instruments of less pretension but of much merit. a stone-dressing machine. A machine for dressing There are two from the manufactory of Conrad stone by power has long been regarded as a great Meyer, of Philadelphia, in neat and very unpretending cases, which combine all the best qualities of the highest rank of pianos. In breadth, freedom, and evenness of tone, in promptness and elasticity of action, and in a combination of everything that is rich and sweet in this description of instrument, he claims to be unsurpassed.

Among cordage, boats, oars, and models of favorite ships, are exhibited two ship-ventilators, by Frederick Emerson, of Boston. These are intended to supersede the ordinary wind-sail now in use for sending pure air into the recesses of ships. The inventor has given much attention to the subject of ventilation, and his success has been honored by several gold medals in the United States. How far this application of his invention may be superior to the methods now in use for the

desideratum, and has been the object of many expensive though unsuccessful experiments. One great difficulty has been found in making the cutting tools of a quality to stand the action of stone, unless at such cost as to render their use unprofitable. This difficulty is overcome by the invention before us, which consists in the employment of chilled cast-iron burrs, or rolling cutters. Iron, as is now known, may, by a peculiar process of chilling in casting, be converted to a diamond hardness, that perfectly fits it for reducing, with great facility and economy, the surface of stone. The burrs made in this way retain a sufficient degree of sharpness for a long time, and can be maintained at a small cost, being wholly formed and finished in casting. In dressing circular forms, the stones are made to revolve, when the burrs, which are mounted in

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