8 MR. CHEVERTON'S NEW GAS POWER-ENGINE. ing powders of inconceivable force.* In an explosion with a large quantity of gas, its sphere of action is more extended, and the fragments are scat tered with an accelerated velocity. To avoid, therefore, exaggerated notions of the danger to be apprehended from the violence with which a gasometer would burst, we must not so much regard the initial force of the confined gas, however great that may be, as the quantity set at liberty. In respect to the magnitude of an explosion, it is the only consideration. Whatever may be its violence, if of inconsiderable extent, we could circumscribe its fury; but on a large scale, though of inferior force, we should in vain attempt its control within any moderate bounds. It is important, therefore, to ascertain the quantity of gas that can be suddenly let loose at any one time, in order to show that it is completely manageable within a space perfectly consistent with compactness. Let an extreme case be taken-an 80-horse power-engine (if more power be required, it will be advisable in other respects to have more than one engine); the minimum and maximum pressures equal to those of 60 and 100 atmospheres ; a sufficiency of gas The rationale of the very different effects of these powders, I imagine, must be this:-The quantity in weight being given, there is, in respect to the detonating powders, a larger proportion which takes the gaseous form, a greater concentration of the elastic fluids in the solid form, and a much more rapid combustion; there may be a greater quantity of æriform products from the same weight of base, and a more inteuse heat for the instant. These circumstances necessarily produce an immense initial force-its development is instantaneous, and produces all the effects of percussion. But there are others which give it a fugitive character, and by limiting its sphere of action, prevent it from imparting a superior velocity to balls. There is a much less proportion of permanently elastic fluid, the high temperature required for the existence of the vapours and volatilized products cannot be main tained for any extent of range, and there is a less quantity of caloric either for this purpose or for sustaining the augmentation of the expansive force arising from heat. generated to admit of 15-double' ~ strokes per minute, and to allow of an average acting power of 40 atmospheres being taken for only onefourth of the time alternately the latitude of space given in the gasometer, the condensing space allowed in the generator at the lowest pressure, and the quantity of liquid convertible into gas, to be respectively equal to one-fourth the bulk of the body of oil put in motion. This supposes the liquid employed to expand in the form of gas under the highest pressure, to a little less than six times its bulk, which is thought to be a sufficiently low estimate even for the carbonic acid, though it is lighter probably than water, and its gas is heavier than air. * From these data it will be found that the greatest quantity of gas which can be instantaneously liberated is about two and a half cubic feet at its greatest density, or 250 cubic feet under atmospheric pressure, occupying a cubical space of little more than six feet dimensions. The liquid in the generator at the time of an explosion would not, of course, as an elastic fluid, contribute to its force--it would only rapidly evaporate. Now this quantity of gas is not so great but that it may be easily controlled, even if it possessed the expansive force of inflamed gunpowder. Though the latter is at least sixteen times greater, let a comparison be ventured on the ground of equality that is, on the assumption that the engine is at work under a pressure equal to sixteen, instead of one hundred atmospheres. What quantity of gunpowder will produce an equal explosion ? From many accurate experiments made by Mr. Cruickshank, it appears that, of 100 grains of good gunpowder, 47 pass into the gaseous form. Taking other data and assumptions from Mr. Robins, viz. that the average specifie gravity of the elastic products is equal to that of the atmosphere, that the specific gravity of gunpowder is equal to that of water, and that the augmentation arising from heat is in the ratio of 4 to 1, it follows that the volume of elastic fluids MR. CHEVERTON'S NEW GAS POWER-ENGIne. at the instant after explosion is 1600 times the bulk of the powder in flamed, and that ten pounds will produce 250 cubic feet. This is a very low estimate of the force of fired gunpowder, especially if Count Rumford's experiments could be relied on, but in which there must certainly be some error. Let it, however, be supposed that this quantity does not produce a greater or more violent explosion than would result from the bursting of a gasometer. Now no one will think the explosion of such a quantity may not be controlled within the boundaries of a cylinder of very moderate strength and dimensions. It is fired from guns and mortars without alarm, and these have to sustain its immense initial force; but we are only concerned to restrain and point its force in a harmless direction, when it is almost spent. Two hundred and fifty cubic feet of gas may be liberated even in a close vessel of that capacity; and if made of wrought iron plates one-fourth of an inch thick, would be capable of withstanding ten times the pressure to which such explosion would subject it. But there is no propriety in closely shutting up the engine: there should be free vent for an explosion upwards. To have additional strength and security, the enclosing cylinder may be made double; the annular space to form the refrige rators, or a common reservoir for water. Let the subject be viewed in regard to compactness. If the safety-cylinder has a diameter of seven feet, and is ten feet high, it will contain all the apparatus of an 80-horse power-engine, and have a clear capacity besides equal to 250 cubic feet, corresponding to the quantity of gas that would be liberated in vase of an explosion. It may still be thought, that though an effectual defence is provided against the pressure of an explosion, yet fragments of the gasometer would be scattered with such 9 violence as to destroy the cylinder or the guards placed above it. Not to mention that these defences may be easily made even musket proof,in fact, indefinitely strong, I would say, let them for once be put to the proofthe experiment would never want to be repeated, and the result would be an undoubting confidence on the part of the public. It should also be observed, that the gasometer, which is the only dangerous vessel, will be very strong and heavy, and that an explosion can scarcely happen in the way of fracture, but from a separation of its parts. Mr. Brunel, 1 perceive, has most judiciously proposed to compose his of only two pieces, and to have the joint at the bottom (this is principally to avoid leakage); consequently, in case of the fastenings giving way, the mass of metal forming its superior part, will oppose such a resistance to the explosion, both from its weight and inertia, that probably it would be projected but a very little height above its base, even if unrestrained. I judge from the recoil of a piece of ordnance, with a bore of half the area of the gasometer. It may excite surprise, that the possibility is admitted of this vessel bursting into fragments. We are too little acquainted with the subject positively to say that the cohesive strength of of the metal would not be gradually diminished by the liquid or its gas under high and long continued pressure, though there may be no immediate chemical action apparent. Liquids, under high pressure, pervade the pores of metals: water, heated under the same circumstances, decomposes glass. It is worthy of remark, that, in such a case, the vessel would not be simply ruptured, as by mere dint of force, but would fly into a number of pieces. The means of prevention belong to the other part of the inquiry, to which we next proceed. (To be continued.) B. C. SIR, The following description and sketch of a method for Heaving in a Ship's Cable, inay merit the attention and adoption of all our nautical merchants, on board of such vessels as use a capstan and messenger. Seafaring persons are not ignorant of the very great expenditure and waste of nippers now used, which must be made from good yarn, and not unfrequently a serviceable cable even obliged to be cut up for the purpose. I propose to substitute wood, and partly iron, or iron nip pers, which shall require fewer hands, and work with greater facility and expedition, as well as be less liable to injure the cable. According to the present mode of heaving in, when there is a heavy swell, or great strain, it frequently happens that the cable runs through all, and is greatly injured by the friction. If the mode I propose should answer, and the expense of trial will be but trivial, the economy will be immense. If you can forcibly bind the cable and messenger by simple means, without injury to either, by means of wood or iron, and I think there is no doubt of the practicability of the thing, a very essential national benefit will be obtained. Description. Figs. 1 and 2 represent the same machinery, only in different views. Fig. 3 is an apparatus on the same principle, but on a different construction. Fig. 1 is an end view of two pieces of iron, AA, box-jointed at the lower end; their width about eight inches each; the would be best made of wood or iron, but thickness must depend on whether they in either case they should taper from the lower part. B is a joint clamp, moving on a bolt through the upper end of that side of A, with a screw through the clamp end of B, and a hole through the head of the screw for a bar lever. C, against the other piece, A, is a continnation of the piece A, slighter, and projecting in the form given. Against this the screw is to act, when the two pieces, AA, are closed. at top, and the clamp, B, shut down, as shown in the perspective, fig. 2. cable and messenger; and fig. 2 repreFig. 1 is open, for placing within it the sents the machinery closed, with the lever and screw for acting, to give the requisite pressure to the cable and messenger. I have the inner edges of AA rounded off, to prevent any chance of cutting or injuring the cable, and let them be scored within, as represented inside of fig 2, to correspond and receive within their score the lay of the cable or chain, to create a greater resistance. I have formed AA angular, for keeping the cable and messenger more securely in position, and, I think, also increasing Lieut. HIGGINSON, R.N. by this form its binding effect. I am, Sir, yours, &c. ENGLISH GRAMMAR. On the external and upper end of that side of A, as represented in fig. 2, underneath the screw, where the clamp is closed, a groove is formed, leaving a shoulder on each side, for the clamp to fit well in. By this means the two opposing strains of the cabie and messenger will bear more equally on the upper and lower extremities of the two pieces, AA, which might otherwise cause a partial side strain on the screw, so as to in jure its worm or thread, and prevent its free action. Fig. 3. AA are two arins, similarly formed to the beforementioned, but differently connected; the lower part, B, is a square bar of iron, horizontally jointed, as shown, about the centre; the bar is continued up as high as C, through the upper end of which form your screw orifice; the piece, A, connected with the screw must be moveable, to slide to and fro on the bar, B, by a groove formed centrical in the under part of A, so as to ride on the bar, B, and connected to the screw by a hole through the central part of A, for entering the end of the screw made smaller at that end, and rivetted on, with a nut to secure it, making it free to turn within the orifice of A, so that the action of the screw will close and open the sliding piece, A, on that side. The piece A, on the opposite side, will be a fixture or continuation of the joint-bar, B. By the action of the screw, when the messenger and cable are placed within, you produce your pressure by the screw-lever; the horizontal joint of B is intended to relieve any strain that might otherwise be brought on the worm and thread of the screw, from the action of the two opposing powers. No. 4 is a bird's-eye view of the machinery of fig. 3. Use old hammock, or matting made for the purpose, to prevent chaffing. I should suppose, that three of these nip pers put on at a time, would on all occasions effect the desired purpose. One hand need only attend at the hatchway, for relieving the screw power and taking off the nipper, and two may attend to the clapping on; so that there needs no number of boys or men, of six or seven, to hold on nippers, besides the difficulty and delay, both in clapping on and taking off, and now and then a hand or two wanted with a knife, to cut and clear many jammed nippers. These nippers must be made proportionate to the size of the cable they are intended for; I can give no accurate judgment of their weight, but, of course, all extraneons weight will be avoided in their formation. If made for chain cables, doubtless they may be made lighter, as the inequalities of the chain present greater facility of resistance, consequently a less powerful pressure would be needed; and if chain messengers can be used with the chain cable (and I see no reason why they should not), the facility of creating a nipping power for heaving in, will be still greater. This powerful steady screw-nipper cannot injure a hempen cable, as long as your pressure is so forcible as to prevent friction by their escape, as is frequently the case with the present nippers; even when the anchor is up to the bows, and ready to cat, down it goes, and labour and time are lost. Objections may be made to the screwpower on account of the wear, consequently, in time, liable to recede from the forcible nip acquired; but this may be removed by a slight wedge applied between that part of the nipper against which the screw presses, and the part through which the screw acts. Or the nipper, fig. 1, may be used, by a simple bar lever power, in lieu of the screw, and the wedge to secure the uip. ENGLISH GRAMMAR, SIR,-I am much pleased to see that you have given insertion to the commencement of a series of articles on English Grammar. The science of language is not so much attended to in this country as its importance demands; and that part which is most attended to is the least useful, namely, the dead lauguages. It is not uncommon that we find persons who can decline hic, hæc, hoc, and gabble for hours about longs and shorts, who cannot speak and write their own mother tongue with even tolerable accuracy; and others will show off with their Parley-vous le Francois, Monsieur, and give us the next sentence in as bad English as can be well put together. I do not deprecate the study of the dead languages, nor of other living languages besides our own; but I do think that our uative tongue is of the most importance, and ought to be studied in preference to all others. I am glad to see this subject taken up in the pages of the Mechanics' Magazine, not only in consideration of its great utility, but in the hope of having some obscure parts more fully explained than they have hitherto been. We have a va riety of grammarians, and scarcely auy two of them agree on all points. By whom, then, are we to be guided? The grammarians differ, and so do also the best writers of the day. I want to see, the disputed points argued and decided, as far as argument cau decide them. This, I trust, will now be done. your Correspondent proceeds, I will, with your permission, notice whatever. points I conceive disputable; and I hope that others, more competent, will do the same. I cannot boast of a classical edu As 121 SICK CHAMBER FURNITURE-IDEA OF A SELF-ACTING PUMP, cation, nor even of a common school I am not satisfied as to the propriety or impropriety of some material alterations in our orthography. Some persons write music and critic, and others musick and critick. Which method is most proper to be followed? May not the be deemed superfluous in all words ending in ic? Again, some write honor, honorable, labor, laborer; and others honour, honourable, &c. Is not the u superfluous in all words of this description? It is not pronounced, and therefore I incline to the omission. It seems to me, that the u should be retained in those words only which are pronounced with the dipthong long, as in mound, mouth, profound, rebound, &c. I do not agree with fanciful innovations in language; but these alterations are already made by many of our best writers, and it is well to create a uniformity as soon as possible. The French at one time wrote many of their passive participles with eu, as leu, peu, seu, veu, which they now write fu, pu, su, vu; and the reasons given by modern French writers for this omission of the e, will apply equally well to our omission of the u in those words where it is not sounded, or does not lengthen the other vowel. These may seem immaterial points, but they are a part of our language, and ought to be decided one way or the other; and I am persuaded that a place in the Mechanics' Magazine will be well occupied in their discussion. Believe me, Sir, SICK CHAMBER FURNITURE. In the parish of Chipping Ongar, in the county of Essex, there are provided for the use of the poor, in the time of sicka.ess, not only bed-linen and a wrap ping flannel gown, but also a large easy wicker chair, with a head to it, a bedchair, and a stand for a candlestick, with a convenient apparatus for a pannikin at the top, in which any kind of liquid may be heated, merely by a rush-light. These articles, with blankets, which are distributed amongst the poor in winter, and are required to be returned in warm weather, are kept at the Workhouse, and may be obtained upon application. The chair, which is also made to answer the purpose of a night-chair, being ried abont than a wooden chair, and has of wicker, is lighter and more easily carbeen provided at a reasonable expense, having cost only I. 6s. It has likewise the advantage of being easily washed, as the lining (which is wadded) is only tied in with tapes, and being hooded, is a shelter to the patient against the wind. The candlestick is of modern coutrivance, consisting of a tube with a kind of hason at the top of it, both of which are filled placed, which, as it wastes in burning, with water. Into this tube a rush-light is is raised up by the water, and kept alit is sufficiently near to the pannikiu ways at the same height, by which means fixed in a frame above it, to warm any liquid which it contains. Observations. The want of some conveniences of this frequently noticed by those who are in kind in country parishes, must have been the habit of visiting the sick cottager or his family. Many a poor person has advisable so to do, by not having any been prevented sitting up when it was thing to sit in but a common chair, which does not afford the support to be found. in au easy chair, nor the warmth and comfort to be derived from a wrapping flannel gown, aided by the lining of the chair; and when the weakness of a patient has rendered a removal from the bed almost impossible, the want of a bed-chair has been ill supplied, by some person supporting the patient during the time of administering either medicine or lies experience in obtaining a change of food. The dificulties which poor famibed-liuen during sickness is very obvi-, that out of a scanty pittance they are ous; nor is it a trifling inconvenience, sometimes compelled to keepa fire during the night, when the state of the patient would not require it for warmth, and when the heat of a candle, if they had the means of supplying it properly, would be sufficient for the purpose of warming any liquid. If it should appear, upon consideration, that these domestic comforts of the sick poor may be provided in any parish, at a very trifling expense, it of alleviating the sufferings of the sick, is not too much to hope, that this mode be adopted by other parishes. and of accelerating their recovery, will. IDEA OF A SELF-ACTING PUMP. SIR,-In your 139th Number you have given another "Idea of a Self-acting. (alas Perpetual) Pump," by our old friend, Robinson Crusoe; whom I trust I shall not offend, when I declare that, like Viator's, it is erroneous in princi |