who had neglected family prayer for better than five years, informed his wife, that it was his determination to resume that laudable practice the same evening; but his wife having engaged a ball at her house, persuaded her husband to put it off till they saw whether the comet appeared or not. The South-sea stock immediately fell to five per cent., and the India to eleven, and the captain of a Dutch ship threw all his powder into the river, that the ship might not be endangered. The next morning, however, the comet appeared according to the prediction, and before noon the belief was universal that the day of judgment was at hand. About this time 123 clergymen were ferried over to Lambeth, it was said, to petition that a short prayer might be penned and ordered, there being none in the church service on that occasion. Three maids of honour burnt their collections of novels and plays, and sent to a bookseller to buy each of them a Bible, and Bishop Taylor's Holy Living and Dying. The run upon the Bank was so prodigious, that all hauds were employed from morning till night in discounting_notes and handing out the specie. On Thursday, considerably more than 7000 kept mistresses were legally married in the face of several congregations.

And to crown the whole farce, Sir Gilbert Heathcote, at that time head Director of the Bank, issued orders to all the fire-offices in London, requiring them to keep a good look out, and have a particular eye on the Bauk of England.

MINOR CORRESPONDENCE.

Ventilation of Coal Mines.-Sir, I feel that an apology is necessary to an old and talented contributor to your pages, Mr. Michael Garvey. For some time past, I have been in possession of a scheme by Mr. G. for ventilating coal mines; but pressing engagements have prevented me from laying it be fore the public, through the medium of the Mecha. nics' Magazine. Under all circumstances, bowever, I cannot say that I experience any regret on account of this delay, since, perhaps, but for the silence observed, by every body else, on the subject of the collieries, we might not have been favoured with the interesting letter of Humanitas, inserted in your last number. The communication that I shall have the satisfaction of placing in your hands, will show that Humanitas does not stand alone in his endeavours to rescue a deserving body of mechanics from personal danger in their avocatious, and personal insult from their fellow men. Where, indeed, is the man that should say to them, "Stand off; I am more useful than thou?" Let but such writers as Humanitas persevere in their endeavours to dissipate those divisive prejudices so amongst all mechanical trades, and such practical men as Mr. Garvey occasionally (lay aside their working tools, to give free scope to their inventive faculties, and we shall soon find whether science is unheeded or declining to that state among practical men, that some of our modern philosophers would lead us to imagine. In a few days, I shall send you a drawing and description of Mr. Garvey's Flan mediately following, some account of

common

his excellent models of the five orders of architecture.. Yours, &c., C. DAVY, Oct. 29, 1831.

Noctidial Globe." If your correspondent, Robin son Crusoe, No. 139, would explain the curious combination of levers that gives motion to his noctidial globe, I should feel myself very greatly obliged to him, as I could wish to mount one in the same manner. I prefer a drawing of the levers, if he pleases, with a minute description, as soon as convenient."-W. O.

Sail-Worked Paddles.-Mr. Editor, I beg leave to acquaint you, that the plan of the vessel with sailworked paddles, given in the last Number of the Mechanics' Magazine, has a very considerable time since been invented and subjected to my mechanical labours. I, therefore, must acquaint you of it; that in case I should come forward with a similar invention, your correspondent, A. B. W. may not accuse me of having copied from him through the medium of your pages. I shall be happy to prove my asser tion to you, Sir, in submitting to your personal view the model thereof, if desired.-Yours, &c. S. T. a Constant Reader of your valuable Magazine, London, Nov. 1, 1831.

Mr. Utting and Mr. Mackinnon.-We gather from a letter of explanation which Mr. Mackinnon has sent us, that he was led by a grainmatical misconstruction of a sentence in a communication from Mr. U. (vol. xiii. p. 112.) to ascribe to him that opinion respecting a future state which Mr. U. has disclaimed (vol. xv. p. 304). We deem it unnecessary to give the letter at length.

Plate Powder.-Sir, Having received many valuable hints from your useful work, I am sorry to find fault with it in any way; but what I wish to advert to is the plate powder, for which a recipe was given by "A Jeweller" in a late Number. This I tried upon a pair of watch-cases, making the mixture as near the proportions as I could with my clumsy scales; but the effect was a total discoloration, and I was obliged to send them to a watchmaker's to be cleaned, when it appeared that a drop of spirit of wine with a little of the powder had found its way into the works, and covered the place where it touched with verdigris.-Yours, &c. A TEA DEALER, Lisson Grove North.

Cause of the Report in Explosions." An Old Sportsinan" thinks the question on this subject "might be set at rest by asking Mr. Baddeley how any noise is made when a gun bursts, and there remains nothing for the air to rush' to?"

INTERIM NOTICES.

The Supplement to Vol. XV. containing Title, Preface, and Index, with a Portrait of Jacob Perkins, Esq., Civil Engineer, engraved on Steel by Roffe, from an original Painting by Howard, is now ready, price 6d.

We shall endeavour to furnish G. L. S. with the information he wishes in our next.

Communications received from N. E. P.-Mr. Bartlett-Iron Base-A Well-wisher-W. R.-Laicifrepus-T. D.-H. H. W.-P. T.-Trebor Valentine-A Constant Reader-Mr. Robert Twiss, Jun. X. Y. Z.-Junior.

LONDON: Published by M. SALMON, at the Mechanics' Magazine Office, Wine-office-court, (between 145 and 146) Fieet Street, where Communications (post paid) are requested to be addressed. Sold by G. G. BENNIS, 55, Rue Neuve, St. Augustin, Paris.

M. SALMON, Printer, Fleet Street.

MR. GARVEY's plan for VENTILATING COAL

MINES.

Sir, I now sit down to fulfil the promise made in my last letter, to communi. cate to the readers of your valuable journal a description of a plan for the better ventilation of coal mines, devised by my friend, Mr. Michael Garvey, and which I believe to be perfectly new.

The prefixed engraving represents an attempt at a section of a coal mine, but necessarily exaggerated in certain parts, in order more fully to exhibit the apparatus. E is a boiler, fed from C by the pipe K, having a stop-cock p to regulate the supply. AAA a pipe, four inches in diameter, passing down the mine, and supplied with hot water from the boiler; BBB a sheet of iron pipe, 18 inches in diameter, through the centre of which the hot-water pipe passes. The large pipe has a number of small ones inserted in the upper part of it (furnished with stop-cocks), which pass to the greatest heights in the ceiling, and within five inches of the top. These admit the foul air (drawn in by the current) to pass along the larger pipe, and into the fires at each end, where it is consumed. HHH are upright or perpendicular shores of timber to support the pipes; G the drafts or openings. The hot-water pipe, being a simple syphon, will, when filled, discharge the surplus water into the cistern D, from which it may be pumped or otherwise conveyed into the cistern C, and used for the steam engine or returned to the boiler in a warm state.

The air in the large pipe will be heated sufficiently by the hot water in the smaller one, as to cause it to rush with considerable velocity upwards in the perpendicular part, thereby causing such a distribution of the current of air in the mine as to prevent any considerdble accumulation of fire-damp. Besides it will have the effect of rendering the mine drier, and consequently more healthy. The pipes may be so placed at the top or the sides, as to be entirely out of the way, should the galleries be low.

PREVENTION OF CONTAGION.

DISINFECTING POWERS OF HIGH TEM-
PERATURES.

Dr. Henry, the eminent chemist, was some years ago requested by Mr. William Garnet, a merchant of Manchester, who is extensively concerned in the importation of Egyptian cotton, to take into consideration whether any effectual method could be devised of guarding against the introduction of the plague into this country by means of that raw material, without incurring the serious commercial sacrifices, which used to attend the enforcement of the quarantine laws on large cargoes of that article.

Chlorine had been suggested for the purpose; but that was found inapplicable, not only on account of its chemical activity on vegetable substances, but of the necessity of washing and drying the cotton, in order to free it from any adhering portions of that powerful agent, the smallest remains of which would be injurious to the spinning machinery. It was represented to Dr. Henry, that, in any method that might be devised for destroying contagious matter, it would be quite essential, that it should be incapable of injuring, by its chemical action, the tenacity of the fibre, as this would unfit the raw material for the operation through which it has subsequently to pass.

After giving much attention to the subject, no means occurred to Dr. Henry of effecting the object in view, but that of applying to the raw cotton such a degree of heat, as while it should do no injury to the staple of the article might, yet be sufficient for the destruction of any contagious virus, which it might have imbibed. That the contagion of the plague, supposing it to be present in the state of fomites* might be rendered innoxious by a temperature below that of boiling water, appeared not improbable, from a fact recorded by various writers, namely, that the plague in countries where it prevails, ceases as soon as the weather becomes very hot; and also from

* Fomites, the plural of fomes, fuel, expresses contagious or infectious matter existing in absorbent substances, such as wool clothing, &c. In this state of confinement, it seems to acquire increased virulence and activity.

various chemical analogies-such as the change by heat of starch into (something like) gum, and of phosphoric acid into pyro-phosphoric acid.

The results of Dr. Henry's experiments with cotton were at first, however, rather discouraging. When raw cotton of ordinary dryness, as recently taken from the bag, was exposed during two or three hours to a steady temperature of 180° Fahrenheit, in a vessel heated by steam of common density, it lost gene. rally between two and three ounces in the pound, and became what is technically called fuzzy, that is unfit even for those operations which are preparatory to its being spun into yarn. But, after the cotton had been left two or three days in a room without a fire, a great change was found to have taken place in its appearance, and on trial, it proved to be as capable of being spun into perfect yarn as cotton employed in the ordinary manner. Manufactured articles of cotton, silk, and wool, were next submitted to the same treatment; and, amongst them, were several fabrics of the most fugitive colours and delicate textures. For three hours they were exposed to a temperature of 180°, and then left a few hours in a room without a fire; after which they were pronounced, by an excellent judge, to be perfectly uninjured, in every respect. Furs and feathers, similarly heated, underwent no change.

The next and most important point to be ascertained was, whether a temperature below 212° Fahr. is capable of destroying the contagion of fomites? It was out of Dr. Henry's power to try the agency of heat on those contagions which propagate the formidable diseases of cholera, plague, scarletina, typhus, &c.; but he thought he might arrive at an analogical inference, by ascertaining its effects on the vaccine lymph. He, accordingly, made a great number of experiments for this purpose, and ascertained decisively that vaccine lymph is rendered totally inert by exposure to a temperature of 140° Fahr.; hence he infers, that all those subtle animal poisons which lie dormant in the state of fomites, are likely to be disarmed of their terrors by the same simple means.

Dr. Henry concludes his account of these experiments (which the reader will find related at length in the Philosophi

H 2

99

cal Magazine for the present month) with the following observations:

"If a favourable result should, however, issue from these suggestions, nothing can be more easy or less expensive in construction, or more manageable in use, than an apparatus for subjecting articles imported from unclean places in any quantity, however large, to the disinfecting agency of a dry heat, without even the slightest injury to the quality of those substances. A double vessel, made of copper or of tinned or cast iron, of any convenient shape, with a sufficient space between the two vessels for containing steam, and an interior cavity of due size for a receptable of the articles to be disinfected, is the essential part of the arrangement. To avoid all risk of the escape of any portion of the virus in an undecomposed, and therefore active state, a pipe open at each extremity may be carried from the receptacle into the flue of the chimney, or, better still, into the fire-place, under the boiler, which will ensure the destruction of the contagious effluvia. The articles should be introduced into the receptacle, not closely packed, but so opened out that every part of them may be exposed to the necessary temperature. If injury should be apprehended from overdrying any substance, a small quantity of steam may be suffered to pass through a pipe from the boiler into the receptacle. At every sea-port to which ships are bound with unclean bills of health, an apparatus of this kind should be provided, on a scale sufficient for the emergency. And on the Continent similar provision should be made at every barrier which is destined to prevent the introduction of contagious diseases. It must be obvious, that these precautions offer no security against the danger of a contagious disease breaking out in a person who has already been exposed to infection, but in whom symptoms of the disease have not yet manifested themselves. Risks from this source constitute, however, a very small proportion compared with those arising from fomites; and they may be easily and effectually guarded against by insulating the person supposed to be infected, for a period of time exceeding that during which the seeds of the disease have been ascertained to be dormant in the animal system. Nor is this proposal meant to supersede the employment of chemical disinfectants, especially of preparations of chlorine, in the apartments of the sick, or their application to articles and fabrics which sustain no injury by exposure to these agents."

INEFFICIENCY OF CHLORINE AS A DISIN

FECTING AGENT.

(From the letter of a correspondent of the Times.) "One of the chief remedies proposed by this writer (the author of an article on the choiera in the last number of the Quarterly Review) to be employed to stop the contagion of the pestilence is chloride of lime. If he knew any thing of the efficacy of this substance, he would know that it has long since been pronounced perfectly useless as a disinfecting agent, and that it has no power whatever in destroying contagion; and should he not be acquainted with the reports made on that subject from Moscow and Warsaw, in the cholera hospitals of both which cities, the chlorine gas was fairly tried and completely failed, let him ask the physicians of the fever and smallpox hospitals in this metropolis, whom the Board of Health took an opportunity, immediately after their appointment, to examine upon this very point. They will tell him that they have long since discontinued the use of chlorine gas, having found, after repeated and long-continued trials, that it was even worse than useless, and that they now place their sole reliance upon cleanliness and ventilation, as the only effectual means of counteracting the accumulation of infection."

WARM BATHS

THE BEST REMEDY FOR CHOLERA.

The Monthly Magazine, of the present month, contains a translation of a letter from Dr. Ucelli, a Russian physician and surgeon, in which the author states, that he has found baths of hot water or steam, together with warm fomentations and acidulated beverages, quite effectual, of themselves, for the cure of the cholera. "Amongst upwards of 2000 patients," he says, "who were under my care, the mortality never exceeded 8 or 9 per 100, and these were principally cases to which I had been called in late, and in which the disease had consequently made considerable progress."

"Scarcely is the patient well seated in the (vapour) bath, when a moist vapour invests his whole frame, and soon a most abundant perspiration causes the vomitting, diarrhoea, and colic to cease. Returning to his bed, the transpiration continues, and in such abundance as to bathe not only the sheets but the very mattresses; this is accompanied by a sen

"The harbour masters of the port of London; and Dr. Hutton, and Alexander Murray, Esq., have all concurred in anticipating the greatest advantages from either removing this old and faithful servant, the bridge, in toto, or of throwing two of its centre arches into one.

"It is admitted on all hands, that the influx of the flowing tide would be accelerated to a very advantageous extent; but at the same time, it cannot be cealed, that great inconvenience would arise to the navigation, above bridge, from the consequent decrease in the depth of the river at low water.

The harbour masters say, that in its present state, by its confined arches, a great body of water is prevented from flowing upwards, the water below the bridge having generally fallen two feet before it becomes level, and the stream ceases to run up.'

This falling of the water below the bridge, does not by any means convey the clearest conviction of the flowing tide meeting with any obstruction. Had they said that the flowing tide stood generally two feet higher below the bridge than above it, an obstacle to its free influx would here clearly be established and understood; and if this latter position be not the case, London bridge would appear, in its present condition, to offer no obstruction whatever to the flow of the tide; but, on the contrary, forms a dam highly beneficial in preventing the ebb tide from escaping with too much celerity.

"It seems impossible to dissent from the opinion of the harbour masters, although in this opinion we are sorry to say, Dr. Hutton by no means concurs that "were the bridge removed, there would at first arise some inconve

* 56, Charlotte-street, Fitzroy-square.