to affordome space for the insertion of these few suggestions. The question is, whether a stagnant body of unwholesome atmosphere, which we generally breathe in rooms, is not to be removed, and give place to a fresh supply of that which is not only more pure, but more healthy. I assert that it can be easily done, and I support that assertion by proposing the following remedies as means for accomplishing the same. If I speak of rooms about to be built, I shall say, introduce into the chimney the outlet which I alluded to in my last letter, and also let there be two or three openings of the same description in the ceiling, which shall communicate also with the chimney or the front of the house. I am aware that these openings in the ceiling have been introduced in some instances, but upon a scale so extremely small, that the idea of their being of the slightest use in (causing a ventilation, is perfectly absurd. I have lately seen two instances in rooms where large numbers are in the habit of assembling; the principle is quite correct, but it is rendered necessary by the outlet being so absurdly small, as to afford very little passage for the imprisoned heat. These openings into the ceiling might be formed of such bold designs, and so arranged, that they would contribute as much to the beauty and style of the room, >as the pattern upon the carpet, or any other part which is intended to be ornasmental.

If I speak of rooms already built, I beg to propose another remedy which ecan be easily adopted, and that at little trouble and little cost. There is a species of manufacture, if I may so call it, introduced within the last few years, for the ouse of man, which, I believe, is generally known by the name of wire-gauze; this wire-gauze heretofore, I believe, has >>been applied to no other useful purpose than that of being affixed to the lower *part of windows, for the purpose of excluding the view of the public from those rooms where parties wish to sit to see the "stir of the great Babel and not feel the crowd." In other words, they are very effective in ensuring protection from the public gaze, whilst they scarcely interfere at all with the view from the interior. So far the purpose is answered, but I want to extend its utility beyond, this point. I want to use it as a medium by which fresh air may be admitted into a

room without inconvenience, and thus it should be done.

Let the upper half of each of two windows in a room be lowered, and let a wire-gauze blind be made to fit in the open space, the consequence would be, that through these blinds the air would be admitted freely without the slightest inconvenience to any one who might be in the room; in fact, so little could even the most delicate be affected by it, that the hand, if held at the distance of three or four inches from the blind, will not be sensible of the slightest current, so completely is it broken by passing through, what Dr. Johnson calls the interstices of the intersections. I propose to have the blinds inserted in the upper part of the window, because I am aware that many persons would imagine, that if they were in the lower half they would be objectionable from their admitting too much air; but the fact really is not so, for any one might sit for hours close by them without the least danger or possibility of catching cold. If, however, they are affixed in the upper half, any apprehension of this being the case is utterly groundless. When the wire-gauze is applied to this purpose, it is not necessary to have it of that fine character I observe it, generally bears, the interstices might be farther apart, and the quantity of air admitted in consequence would, of course, be much greater. In the coldest weather the windows in any room might be kept open with these blinds fixed up; for if it be asserted that the cold would be felt too severely, my argument as to the act of ventilation is instantly supported, for it is thereby proved that a body of fresh air is introduced; and to prevent the same being at all inconvenient, you have only to close the windows to such an extent as to reduce the supply, and bring it within a habitable temperature. Any room having these blinds, and the opening into the chimney, which I have before referred to, would be unable to contain even for half an hour the rising volumes of cloudy exhalations puffed forth with vigour from one dozen of Cabana's best Havannah bristling from the mouths of confirmed smokers.

Now that I am on the subject of the wire gauze, I may be allowed to express my surprise that it has not yet been used in gentlemen's carriages and stagecoaches. Is not every one aware of the

extreme danger of having the window of a carriage down to those who sit on the back seat?-it is not only dangerous, but unpleasant, to sit exposed for hours to such a body of cold air coming through a contracted space;-at night, too, four persons are cooped up in a mail-coach, breathing such an atmosphere as would "destroy life, unless by the periodical opening of the window. Let these wiregauze blinds be added to each window, and in cold or heat, in winter or summer, through them will you breathe as pure and wholesome an atmosphere as those enjoy who sit on the outside. The indisposition which persons feel after travelling inside all night, and indeed during the day, in cold weather, arises "principally from the impure air which they have been breathing during their journey. If these blinds are affixed on each side, an abundant supply of air is admitted, and in a way to be neither unpleasant or attended with any danger, which it always is to those who sit on the back seat when admitted through the open window.

Every one must be aware of the benefits arising from a thorough ventilation in every house, and in every room in every house, but more particularly in hospitals and in houses where the poor congregate and are maintained in great numbers; and, in fact, in all places where large bodies of the population are brought in contact. If, therefore, any observations of mine should be the means of effecting this, or inducing others to turn their attention to the subject, and thereby effecting it, my purpose will be fully answered, and I shall rest satisfied at having contributed towards the establishment of a system which perhaps had remained otherwise neglected, and one which I am confident will not only contribute to increase the personal comfort, but also improve the general health of the great mass of the population.

I am, Sir, yours, &c.

M. C.

MR. MACKINTOSH'S PERPETUAL MOTION NAUTILUS IN EXPLANATION. How, then, could Mr. Mackintosh, his magnet being powerful enough to suspend his bullet, and thereby nullify its gravity, still expect that the said gravity would exert its

power in causing the descent of his wheel." NAUTILUS, Dec. 11, p. 222.

"It must be plain to every one, that gravity, the very power which was intended to give motion to the wheel, is completely neutralised by the power of the magnet."TREBOR VALENTINE, Jan. 28, p. 315.

"I know that the wheel will not, and *I know also the reason why it will not, go; but Nautilus has not yet made that discovery" "his attempt (to do so) is a complete failure."MACKINTOSH'S REPLY TO NAUTILUS, Jan. 14, p. 282.

Sir, I trouble you with the above quoted short extracts to show Mr. Mackintosh that I am not singular in my opinion of the true reason of his machine being no go. Perhaps, having allowed sufficient time for other competitors in the solution of this great problem to have come forward if they would, Mr. Mackintosh will now enlighten your readers by revealing his explanation, which he declares he has hitherto kept in imo pectore, for the purpose of exciting a laudable emulation amongst your ingenious correspondents. At the same time, it will be only fair that he should demonstrate that my explanation of the no-going propensity of his wheel, is the great failure he asserts it to be.

One word as to the previous portion of his reply; touching the moon's rotation, he says, "I readily grant the correctness of his (Nautilus's) views with respect to the imaginary axis.” What is to be inferred from this, but that Mr. Mackintosh supposes that the moon's axis is not imaginary, but real and bona fide? in fact, that there is something like a goodly roasting-spit thrust through and through, with perhaps a protruding peg at each end for the man in the moon to hang his hat upon. As for the assertion, that Kinclaven has been knocked on the head with the lump of lead on the arm of the fly-wheel, I leave it to himself to deny it; I can find no marks of the dent in any of his letters.

I remain, Mr. Editor,
Your obedient servant,
NAUTILUS.

Feb. 5, 1837.

AN ARITHMETICAL QUESTION.

The late Dr. Hamilton, of Aberdeen, -in his excellent system of arithmetic, asserts, that the interest of 10007., at the

A Good Site for a Hero.-The statue of the Duke of Wellington, for which upwards of 70007. have been raised, chiefly among City magnates, it is decided shall be placed between the Bank and the Mansion-House, at the entrance of the street (King William-street) leading to the bridge, for his share in promoting the erection of which the statue is (ostensibly at least) to be raised to his Grace. It will stand, most probably, on the site of "the great Globe itself" (i. e. the Globe Insurance-office), which, now that Princes-street approaches towards completion, certainly stands sadly in the way, and calls loudly for removal as little better than a com mon nuisance!

An expected Arrival.-Orders have been received in Egypt from the Trustees of the British Museum for the immediate removal to London of the fine colossal statue of Sesostris, which, ages since, ornamented the centre of the city of Memphis.

Taylor's Scientific Memoirs.-We are sorry to find, from the Advertisement prefixed to the Third Part of this work, which has just appeared, that it has not attained to a sale sufficient to remunerate its spirited projector, and ensure its permanent existence. It will be a sad slur on the scientific world if a periodical so much called for, and even

To be continued monthly.

so essentially required, be suffered to fall to the ground for want of patronage, especially as Mr. Taylor looks for no pecuniary reward for his own valuable services, but expresses his determination to continue his labours, if only a sufficient number can be sold barely to defray the unavoidable expenses of publication. By the way, we may as well remark, that this Third Number forms a part of Vol. I., which will include four Numbers, instead of two, as stated in our 704th No.

"The Air hath Bubbles." - Air-ballooning is likely to be turned to practical use at last. The "Aeronautical Association, for applying Aerostation to the Purposes of Geographical Survey," is already in operation, and has progressed so far as to open an office, to receive applications for the "four thousand shares, of two pounds each," which are to compose the capital of the Company, "one half to be paid on applying for shares!" As soon as the subscription list is filled, the Association will commence its labours by taking a minute aerial survey of the interior of Africa, for which purpose aerostation presents such tempting facilities, especially with the assistance of the trade winds, blowing constantly in one direction, so as to render the steering of the balloon a matter of infinite ease,-or rather to do away with the necessity of steering at all! This is certainly one of the most promising speculations in the market, but we are not aware that the shares of the Association are yet at any very high premium.

Novelty at a Discount.-The New Smithfield at Islington has now given up all competition with its too firmly-established rival, and the "public-spirited projector," thoroughly disappointed in his hopes of realising a fortune out of the "tolls" so specially secured to him by the Act of Parliament, on whose omnipotence he relied, has offered the concern (at no very high price, it may be presumed, under existing circumstances,) to the Common Council of the City of London.

Mr. Colliers Boilers,-Sir, In reply to a note in your last Number, I beg to state, that not having the slightest wish to be considered as personally opposed to Mr. Collier, I withhold my name. The observation I made in your publication was on public grounds, I therefore expected Mr. Collier would as publicly answer it.-I am, &c. T

H

Feb. 13, 1837.

The inconvenience that frequently arises from the defective construction of the spring-valve generally used in gasestablishments, has led to several contrivances to obviate the difficulties that are continually presenting themselves. A perfect hydraulic gas-valve is, in my opinion, the only remedy for the evils that are complained of. Numerous attempts have been made by engineers to introduce an effective apparatus, and some very clever machines of this description have been published at different times in your Magazine.

It appears to me that the invention, of which I now beg to hand to you the accompanying drawing, is possessed of the necessary mechanical arrangement to render it a perfect air-tight valve. The inventor is Mr. Joseph Hutchison, father of Stephen Hutchison; many of whose improvements in gas-machinery your pages have made known to the world.

A valve precisely upon the same principle as that shown by the drawing was constructed by that gentleman in the year 1812, for a West India merchant, for whom Mr. Hutchison was at that time building a gas-apparatus on extensive premises opposite Meux's brewhouse, in Tottenham-court-road. This was previous to the period when the streets of the metropolis were first lighted by gas, and before the original Company (the Westminster) commenced operations, or obtained its charter.

For many years, after the above premises were vacated, the apparatus alluded to was forgotten and neglected, and it was only during an accidental conversation which I had with Mr. Joseph Hutchison about twelve months ago, that he happened to refer to this invention.

As it is likely, from the simplicity of its construction, to be remarkably well adapted to suit the purpose of a station-valve (it being now used as such on the Continent), I avail myself of the excellent opportunity your periodical affords of making the invention known for the benefit of gas-manufacturers.

Description.

d is a cast-iron tank; Bb are two cups attached to the screws ff; hh are iron stays bolted to the top of the tank

which in conjunction with the rods, ee guide the direction of the screws; a a are hydraulic joints for the purpose of preventing an escape of gas when raising or depressing the cups. Cc are outlet and inlet mains. The inlet main C is represented as being sealed against the entrance of the gas by means of the water which the cup B has taken up from the reservoir i; while the outlet c, in consequence of the seal cup b being lowered, permits the free escape of the gas to the street or district mains.

CLOVIS.

MEDALLIC ENGRAVING STATEMENT OF FACTS IN REPLY TO MR. JOHN HENNING'S CHARGE OF PIRACY AGAINST

LACHEVARDIERE AND CO.

Sir,-A letter from Mr. Henning, respecting the conduct of Lachevardiere and Co., having appeared in the Mechanics' Magazine of the 4th inst., I request leave to reply to it by a statement of facts. The contemptuous

manner in which Mr. Henning is pleased to speak of the engravings by M. Collas, published by that firm, does not, I think, require further comment than will be found in his own correspondence, herewith forwarded -except only to direct attention to his admission, that he has just entered into an engagement with Mr. Bate for the publication of a rival work. This, I admit, ought not to influence his judgment; whether it has done so, I shall leave your readers to determine, strictly confining myself to the specific charges affecting moral character which this person has dared to bring against Lachevardiere and Co., and which you have somewhat incautiously ventured to publish. The wrongs of which Mr. Henning complains are, "of foul robbery and shameless appropriation of his laborious works from the Parthenon and Phygaleian marbles;" of " the unjustifiable omission of his name in the letterpress of the Trésor de Numismatique;" of "the wholesale appropriation of his works to the ruin of their legitimate sale, and the blasting of his reputation;" of "the atrocious piracy of the Company by the seizure of the Canterbury Pilgrimage' of his late son;" lastly, "that having [in 1836, observe] spoken be. fore the Committee of the House of Commons of the unjustifiable omission of his name in the Trésor, he was by a trick,' an unworthy manœuvre,' induced to write a letter to the Chairman of the Committee, acknow. ledging that he had since seen a copy of that work with his name in it, which letter is now shown about with the intention of impugning his veracity."

Now, if I desired to impugn Mr. Henning's