pressed down on coming into contact with any rough surface in the flue. The edges of the scrapers are turned down, in order to facilitate their getting over any projection that may occur in the passage up the flue of the machine. To have particular cleanliness, there should be a chain down each flue, to be hooked up out of sight of the fire-place when not

in use, so that the before described machine might be at once attached and drawn up, instead of letting a chain down the chimney each time, which would of course carry with it some portions of soot. A small windlass, capable of being moved to each of the flue-doors, would be requisite, in order to get the machine up the chimney, with the soot it might collect. The way to sweep a flue with this machine should be this:-Attach the machine at the bottom of the flue to the hook on the chain, then wind it up the chimney till it arrive at the door, then sweep the upper part of the flue as before described; the machine being allowed to remain at the place to which it was drawn till this be accomplished, and which would, of course, catch the soot falling from the action of the broom. Any soot which may hang around the scrapers should be swept into the leather bag; and then, having stopped the action of the springs in the inside of the machine by means of the screws e e e e, (fig. 3,) withdraw it out of the door-way, remove the soot, take it down to the next fireplace, the flue of which is to be swept, and proceed as before. At the enlarged part of the flue, round the fire-place, a small hand-brush should be used to remove the soot. A machine of the nature here described might be kept in every house of good size, and worked by the servants, who, for their own sakes, would be as cleanly as possible in its use.

The next and last method I have to propose, is perhaps more for the sake of exhibiting a very novel mode which has occurred to me of effecting the object in question, than as a means likely to be of good use or general adoption; but if not of use itself, it may in the minds of others suggest some plan of greater utility than any yet described. a a, Figs. 5 and 6, is a metal vessel capable of sustaining a considerable pressure of air, forced into it by the pumps b b b b ; cc, is a stop cock or valve for shutting off from, or regulating the pressure of air in the leathern hose d d. This hose must be made perfectly air tight, and sufficiently strong to resist a considerable pressure from within; e e is a leathern bag, at the throat of which a valve is placed, as shown enlarged in fig. 7, and from which to the air-vessel a, is a strong string of any tough material for regulating its action. Round the leathern bag are placed

steel springs to cause it to collapse when the air is emitted therefrom; at the top of the bag is placed a flexible feeler ƒ, made of whalebone, or any such material, with a round knob of any hard substance at top. To use this machine, first condense air into the vessel a; when deemed sufficiently powerful, having the hose ready to project up the chimney, turn the tap c, which will allow the compressed air to flow up the hose and give it considerable stiffness, yet retaining great flexibility; on the air passing up the hose it will (the string being slack) force the valve to the top of its seat, where it will remain so long as the pressure in the hose shall last, and the string be untouched; thereby preventing any air getting into the bag b, which, therefore, in consequence of the outside springs, will be in a closely collapsed state, and offer no impediment to the free passage of the hose up the chimney. When the hose has been forced sufficiently high up the chimney, the string communicating with the valve is to be drawn till the side aperture of the valve, and the one leading into the bag correspond, where it is to be kept by means of any small apparatus fixed in the air vessel. On the condensed air being admitted to the bag, it (the bag) will of course distend, and fill the aperture of the flue. When it is to be drawn down, the soot, (if the edges of the bag, which are to be made of tough flexible leather, have sufficient hold of the sides of the flue,) of course coming before it, should the bag stick in the flue at any part, or should it be necessary to go over any place a second time, or more, the valve string is to be further pulled down and there retained, till the whole of the air in the bag becomes excluded; the bag, from the pressure of the springs, will then again collapse, and permit the upward motion of the hose to any height in the flue required; by then letting the valve go, it will, by pressure of the compressed air, resume its position opposite the aperture into the bag, if the string communicating with it, be set, for its assuming that station; otherwise, it will go to the top of the valve seat, and preclude the emission of air in any direction, when the bag will again become filled with air, and the process for bringing the soot down the chimney may be continued.

Here I beg, for the present, to con

clude my suggestions under this head, and to hope, that the plans I have submitted to you may meet with immediate consideration from your numerous readers, and if approved of, speedy adoption. Let the barbarous plan of employing little children in the most humble of occupations (viz. chimney sweeping) stop. Let us not even wait for the arrival of that time, however short it may be, which our legislators have fixed on for doing this justice to humanity; but let us put it down with one accord immediately. Why, for a single moment beyond what is absolutely necessary should we protract the sufferings of these poor infants? Even should my plans not succeed, where can be our boasted acquirements in mechanics, if there is not another, ay, twenty other plans forthcoming for effecting this object? And surely from some of these, something like an efficient process could be obtained-some cheap and simple process-some such process as the occupants of houses, or their servants, could use with facility-some process which, from its cheapness, would cause its adoption-if nothing else could work on the feelings-and this attained, Necessity, a law stronger than the wisest of us could frame-would cause master sweeps to desist from their wanderings, and to withdraw from suffering, and from the pitying eyes of every walker of the public streets, the wretched objects of our commiseration, the "poor little chimney sweeps."

Should this be accomplished from my suggestions, my gratified feelings will indeed amply reward me.

I am, Sir,

Your most obedient servant,

JAMES A. EMSLIE.

P.S.-Sir,-Allow me to add, with respect to the rope and weight-brush mode of sweeping chimneys, that the weight may be inserted in the heart of the brush, which it can readily be, by having the whalebone or cane fixed on to strong leather, and this sown round the weight. The injury the pargetting of the flue is said to derive from the action of the weight in the method at present in use, will, I think, by these means be entirely obviated.

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HARTLEY'S FIRE-PROOF BUILDING-FIRE PREVENTIVE COMPANY'S CEMENT. Sir, I am sorry that the shortness of Col. Macerone's memory should have betrayed him so much into error on the subject of fire-prevention, as at this time to recommend it to my attention. I really imagined that, so far as I was concerned, that topic, if not altogether exhausted, was certainly threadbare.

I have already repeatedly denounced house-building-have constantly advoour present highly inflammable mode of cated the general employment of fireguards, incombustible draperies, and other preventives-and have more than once suggested the "sure preventive," (alum solution,) for rendering cotton and similar fabrics partially incombustible. Mr. Hartley's method of protecting buildings, with all the other intermediate projects for preventing the occurrence or extension of fires, down to the introduction of the "Patent Firepreventive Cement," have each, at different times, been advocated by me in your by-gone volumes.

The old motto, of "Prevention better than cure," has been conspicuously set forth and illustrated upon many occasions.

I am truly sorry to find that the gallant Colonel entertains such incorrect notions with regard to the fire-preventive cement, which he deridingly describes as "plaster made of Roman cement and size." Had he witnessed any of the highly satisfactory trials and experiments which have been made with this cement, in London and in some of the provincial towns, most of which stand recorded in your journal, he would have been convinced of the antiphlogistic powers of this preparation, and of the vast benefits which must attend its extensive employment. Col. Macerone states that "beams of wood may be charred by fire through iron plates, but will not break into flames without a current of air is admitted." The cement in question is still more efficacious in this respect; the iron being a good conductor of heat, the charring process goes on very rapidly beneath it; the cement, on the other hand, being an excellent non-conductor, the charring goes on much more slowly. In fact, under circumstances where charring would inevitably take place beneath iron plates, it would be completely prevented by the cement.

66

Colonel Macerone confounds this "cement" with common plaster;" he might almost as well compare iron to wood.

I beg it to be distinctly understood, that I am not at all disposed to cavil about which is really the best fire-preventive process; right glad should I be to see any protective plan, (even though it were the least efficient,) generally adopted. I am only vexed to see so much apathy prevailing with regard to this subject, that no preventive measures whatever are adopted; and even the cure is left entirely to those whose sole business it is supposed to be.

So thoroughly incorrigible have we now become, that all the legislative enactments-which, if carried out, would do much to prevent the spread of fireare become dead letters on the statutebook. Any such preventive law as that suggested by Col. Macerone, at page 60, would be denounced as an outrageous infraction of the "liberty of the subject."

The general employment of incombustible stairs, whether of stone, iron, slate, or even wood effectually protected by cement, would, I have often asserted, and again repeat, completely change the character of London fires. Beyond this, any protection afforded to the partitions, ceilings, &c., either by Mr. Hartley's, or any other effectual process, could not fail to be highly advantageous.

1 several recent instances, public buildi78 have been constructed in a fire-proof, or partially fire-proof manner, and it is devoutly to be wished that the same principle may be adopted in domestic dwellings, where, although property to an equal amount is not at stake, there are lives to be preserved, which are of far greater consequence. I remain, Sir, Yours respectfully,

London, January 24, 1842.

W. BADDELEY.

ON MR. R. ARMSTRONG'S NEW THEORY of diffusion. BY C. W. WILLIAMS, ESQ.

(Continued from page 63.)

But this Daltonian system of separation-diffusion, (meaning Mr. R. Armstrong's new version of it,) appears to be miraculously endowed with the still more

extraordinary, and even discriminating faculty, not only of separating the gases, but of distinguishing those which are useful and combustible from the useless and incombustible! This, indeed, would be "extraordinary-if true." Thus we find that, according to the new version, "the lighter gases, which constitute the most valuable part of the smoke, have, according to Dr. Dalton's law of the 'diffusion of gases,' before referred to, a natural tendency (not to mingle and become diffused, as Dr. Dalton thought and wrote, but, hear reader,) "to leave the carbonic acid gas," (itself the heaviest of them all,) and rush into the ash-pit, as into a vacuum; at the same time carrying the light carbonaceous matter with them." Mr. Armstrong may well say of Mr. Cheetham's plan, which brings such impossibility-working into action, "I believe it to be one of the greatest discoveries of modern times." He might with the greatest safety have said, the very greatest.

But he describes another peculiarity, with respect to the diffusive faculty of atmospheric air, which the great Dalton himself never even dreamed of, and which is thus referred to. "The atmospheric air, which is essential to support the combustion of those gases, not having this diffusive tendency to so great an extent, (how this curious fact has been ascertained does not appear,) requires to be supplied by artificial means, and for that purpose a very small fan is necessary.' Hear that, Dalton and Graham, whose names are pressed into the service of this new theory of diffusion. Mr. A., with great sagacity and penetration, (that is, the penetration which enables him to see farther into the mill-stone than the man who picks it,) observes, "Here the question will no doubt occur to many, as to what is the probable effect of this necessary strong draught, or blast, against the boiler bottom," (from the very small fan!') This, we are told, is an important question; but he adds that, fortunately, it admits of being easily answered by any chemist who duly considers, (and understands,) the rationale of the process as above given." Undoubtedly for any chemist who can understand, not the rationale, but, in plain English, the absurd nonsense of "the process as above given," can have no difficulty in answering any question.