WALKER'S HYDRAULIC ENGINE. f 211 cylinders are closed at their lower extremity H, by valves opening upward. On turning the handle A, a rapid motion is given to the pinion-shaft and eccentric, which has an inch and a half throw; the connecting-rod d, being_attached intermediately to the beam E, a throw of three inches is given to the elevators, which, thus receiving a rapid alternating motion, deliver a stream of water from their nosels I, into the cistern or receptacle, from which it flows in any required direction. The second engraving shows an arrangement for drawing water by means of this apparatus, from wells of a greater depth than could be advantageously accomplished by a single lift. E is the working beam to which two elevators are attached, the first, gg, raising water from the reservoir R, into R', the former being supplied by the second elevator g'g', from the well W. The pinion-shaft is in some cases fitted with two, three, or more eccentrics, which give motion to a corresponding number of elevators contained within the same frame, so as greatly to increase the power of the engine, without adding much to its bulk. It will be apparent that as the one elevator, with its contained column of water, is exactly counterbalanced by the other, the machine is constantly in a state of perfect dynamic equilibrium, and therefore the motion communicated to the machinery, and thence to the fluid, produces a direct action, raising the largest quantity of water with the smallest possible expenditure of power. What the capabilities of this engine may eventually prove to be, remains to be ascertained; in the machines already completed, the quantity of water raised far exceeded the performances of any description of pump hitherto employed; but as none of the machines were sufficiently large to employ the whole power of a man, mechanically considered, no data have yet been obtained upon which to found any calculations. As the matter progresses, however I shall have much pleasure in communicating the results, and remain, Sir, Yours respectfully, W. BADDELEY. HYDRO-PNEUMATIC BUFFERS. Sir,-In the February Part of the Mechanics' Magazine, which has just reached me, I find two articles having reference to my Hydro-pneumatic Buffers, described in the No. 956, for December last, the first signed "N. N. L.," the second, E. Heydn," whom I presume to be the person who has been for some time shop-foreman in the carriage department of the Dublin and Kingston Railway Company's repairing establishment. I dislike, extremely, what is usually termed controversy, which seldom has truth for its object; and should not now ask a place in your pages for a few remarks upon these communications, did, not the latter contain averments and insinuations of plagiarism on my part, which are as untrue as they are ungracefully put forward, and which I beg permission, in the first instance, to refute. Some time in December, 1835, or January, 1836, a Mr. Dawson, a highlyintelligent coach-maker of this city, called upon me to enquire the cost of a cast-iron cylinder with open ends, bored true, about 4 feet long, and 4 or 5 inches diameter, which he stated he wanted for an experimental purpose. I had known Mr. Dawson as a railway carriage builder previously, and almost my immediate reply to him was, "that I could guess what the experiment was-that he intended it for an air-buffer;" and I then at once told him that I had previously given the subject some attention that air-springs for various purposes of draft, &c., had been long ago proposed-that they never had been made to answer, in consequence of the impracticability of making a piston or stuffing box air-tight -and that I considered the only road to success was, to confine the air by a liquid, such as water. I further, on the moment, sketched the general plan for the hydropneumatic buffer, such as it was afterwards executed. Mr. Dawson had asked the cost merely of a bored cylinder: he now admitted it was for an air-buffer, and that his plan was simply a piston on the middle of a rod passing through stuffing-boxes in the otherwise close ends of the cylinder. Having made proper drawings of my scheme, I showed them to Mr. Dawson, who agreed to make the experiment on my plan, I guaranteeing the cost not to exceed a certain sum. The apparatus was executed, and put to work by me, as already stated, without improvement or suggestion on the part of Mr. Dawson or any one else; and the actual cost was nearly double that guaranteed and paid by that gentleman. I am, hence, not indebted to Mr. Dawson, Mr. Heydn, or any other individual, either for the distinguishing principle, or for any one of the details of this sort of buffer, which I am therefore justified in calling MY hydro-pneumatic buffer ; and the full right and title of inventorship to which I thus formally reclaim. What claim Mr. Heydn may sustain to having been the proposer of the plan meditated by Mr. Dawson I do not know; but I have no recollection of Mr. D.'s ever mentioning his name to me in connexion with it, (although I believe he was then employed by him in some capacity;) but granting Mr. H. the full credit of it—admitting that, in 1835, he "proposed to have a piston to compress air at atmospheric pressure in a cylinder, as a simple substitute for railway coach-buffers "then he simply proposed to do what a score of others had tried to do, and failed, before he was born. Air springs in this form were proposed in France in the time of Vaucanson; they were proposed and tried by Edgworth on wheel-carriages-were patented, as applied to draft and to harness, twenty years, or more, ago—were proposed to be used to ease the draft on the track-lines of canal boats by, I believe, Sir John Robison-are mentioned by Dr. Gregory-and had been talked of as applicable to buffing, by me, to various engineers, long prior to 1835, to whom I found the idea was by no means new, but who all concurred with me, that the impracticability of confining the air was a fatal objection. So much for the originality, even of the crude and imperfect notion ; but now let us for a moment consider the "decided improvement," the plan of plans, which in the year 1842 Mr. H. brings forward to supersede mine. To avoid prolixity, the reader must refer to his figure, (page 139.) He proposes a cylinder having a solid packed piston, with a rod passing through a stuffing-box in the cylinder cover at either end, a valve opening inwards in the middle of the length, and a safety-valve outwards. Now, I omit all consideration of the pro HYDRO-PNEUMATIC BUFFERS. portions of this affair, or of its details. I confine myself to a single point; and I affirm that, before a buffer of this sort were at work one week, both pistons would be found as near as they could get together, about the middle of the cylinder; and why? Neither the pistons nor the stuffing-boxes can be made air-tight; and hence, although the blow may be but momentary, (which is not admitted, however,) yet at every blow a small quantity of air would make its way out of the middle portion of the cylinder, pass the piston, and get between it and the cylinder cover, and there being nothing to remove this again, and its quantity being continually increased at every blow, the two pistons would soon get most lovingly together in the middle. But assume this not to be the case-assume, as Mr. H. does, that his pistons are absolutely air-tight-then, what is the use of his valve opening inwards? for, as no air can escape from the cylinder, but by passing the said air-tight pistons, and the cylinder is already full, no more can be drawn into it, after approach and on separation of the pistons, and so the valve is useless, unless as an adjunct to the preposterous safety-valve. We have therefore a very pretty specimen of reasoning in a circle. What the learned writer means by the "rarefied air in the centre," on "the approximation of the pistons," is hard to say, unless, being an Hibernian, he mean condensed," when he says "rarefied:" this is the more probable, as he ingeniously says his pistons, when relieved from a blow, "collapse"—that is, they collapse away from one another! But enough of Mr. H.'s invention. Now, as to his observations on my buffer in use upon the Dublin and Kingston Railway, it might be enough for me to repeat, that I lost sight of it and the subject; and that, had I not thought the original construction needed improvement, I would not have designed those subsequently proposed by me. The first time I ever tried it along the line was with one carriage alone, after an engine, in which there was no one but Mr. Bergin, of the Dublin and Kingston Railway, and myself. On suddenly stopping and starting, the check was no doubt hard; but not more so than with Mr. Bergin's own buffers under similar circumstances, viz., the traction of a 213 single empty carriage, violently started, and as violently stopped; but I on two or three occasions travelled in it as part of a train, and could perceive no difference in the buffing from the other carriages. There is no doubt the friction of the cupped leather piston was too great, and hence, that the piston would commonly remain, perhaps, at three or four inches to one or the other side of the middle of the cylinder; but this is perfectly unimportant. The air-vessels were under the seats, and not inconvenient: the weight of the whole apparatus, full, was only about 94 cwt.; and hence, any objection on this score is preposterous, especially on a line where some of their first class carriages have six wheels, and six or more huge springs, and solid 24-inch round iron buffer-rods; while this affair was in one of the worst and oldest of their light third-class carriages, which, if still in existence, must be a truly venerable article, but probably is so only in the sense in which a gun remains the same which has had a new lock, stock, and barrel; or in which it is said, the king never dies. It is quite likely the stuffing-boxes often leaked water for want of attention; but if they did, how much more would Mr. H.'s stuffing-boxes leak air? I need not, however, pursue his remarks on this part of the subject farther: their ill-nature is as transparent as their irrelevancy to the principle in question, which is, the rendering an elastic fluid confinable as a spring by means of a liquid; and not whether the details of the method by which this was first attempted were perfect or not. I must add, however, that Mr. H.'s observation, that its being on the Kingston line, in the midst of a different system, was only so in form, and not in system, &c., is founding a sophism upon a wilful misconstruction of my words. True, it was, as I stated, a thorough buffer," but different in structure and management from every other buffer on the line; and, I will add, capable of bearing shocks that none of them could stand. 66 The succeeding observations about my proposed upper, or top buffer, are scarcely worth criticism. Either I have been very obscure-or this writer is so obtuse, as to have wholly mistaken the very ground of my proposal. I am so fully 66 convinced, that a "coach body" will withstand no shock, that the very aim of my plan is to provide something in its place that will, and place it so as to receive the shock. The lever of the "first order," is very learned, though somewhat out of date as mechanics now stand; but, unfortunately, it should be, a lever of the second order," as here talked of. Neither is there any mistake about the place of the centre of gravity of a loaded railway carriage, as, if necessary, I shall take occasion to prove, with permission, in your pages. Mr. H. leaves out, "loaded;" perhaps this seems to him unimportant! Mr. H. can state from much experience, "that in nine cases out of ten, whatever be the nature of a collision to a railway train, the coaches are never totally upset" Did Mr. H. ever see a collision, or the results of one, beyond the precincts of the Dublin and Kingston Railway? Never. How many collisions have there been upon it? Two, or three at most. This is the "much experience" from which he makes an induction of nine cases out of ten; and it may be questioned, did he ever witness these two or three collisions? I did not. Yet, I am credibly informed, that in one of them, some of the carriages were thrown right over the others, -and why? Because the buffers were below the centre of gravity, and there was no resistance to motion above that point. A capsizing, or throwing off the rails, has attended every known collision. Mr. H. does not know, but other people do, that what is called a "statical couple," cannot be equilibrated by any one force, or by any number of forces, applied at one point, or in a line at right angles to the arm of the couple. Yet, this is what is attempted to be done by the present arrangement of buffers of whatever system. All that is said about the necessity of the top buffer on my plan being of equal size and strength with the lower ones, only shows the writer's imperfect comprehension of the subject, as must be evident to every competent judge, i. e., to every mechanic who unites theory to practice: I regret to have occupied your pages at such length, with matter comparatively uninstructive to read, and disagreeable to me to be obliged to write-and willingly turn to your correspondent "N. L.," whose gentlemanly style is in pleasant contrast with that of the paper just considered. There is a great deal of ingenuity in the plan proposed by this gentleman, for buffing the recoil of the buffer, by bringing it up against a second body of air; but it is a provision against an evil that does not exist in practice. No such thing actually occurs, (even in a large model,) as the plunger being driven out against the fillet of the cylinder with a sudden shock-or concussion-and for two reasons. In the first place, in the case of collision of two such buffers (say in train), the driven-in plunger cannot return outwards faster than the opposing buffer or plunger, permits it by resilience from it; but as both buffers are imperfectly elastic bodies, this velocity cannot be as great as that with which the plungers were driven. Further, the resilience of the buffer impinged upon, has a tendency to move uniformly, while the return stroke, or motion outwards of the impinging buffer, has a tendency to accelerated motion. Lastly, the friction of the stuffing-box gland is at all times enough to prevent any perceptible blow on the fillets, although unaided by the two former causes of retardation. The fillets, I should have stated, also have a collar of leather between them, against which they mutually abut. But supposing that these were real conditions to be provided for, I much fearindeed I feel authorized to affirm-that the method proposed would not meet the difficulty. First, because the centre diaphragm, or piston, could not be kept tight, being nearly inaccessible, and because the glands could not be even made tight from the practical difficulty of adjusting three perfectly coincident bearings on an absolutely rigid bar, such as the plunger is: the greatest practical difficulties also would attend the equation of the glands, and their necessary packing and fillets in connection with such a cylinder, the bore of which, and hence the diameter of the piston, being larger than that of the end glands inside the fillets. All the moving parts requiring attention, &c., would be doubled in number, and more than doubled in liability to derangement, and it would be very difficult to attach the outer cylinder to the under carriage in a substantial manner, ON THE MANAGEMENT OF FURNACES AND BOILERS. and leave it free at both ends. These are all mere practical objections in detail, which, however, seem to me conclusive, as to the inapplicability of the contrivance, even if it were necessary, which it is not. The plan is, nevertheless, ingenious, and perfectly correct in principle. Oil, in place of being a better fluid for these buffers than water, is about the worst possible; it is nearly as hard to confine as the air itself, and will break out of joints which are perfectly watertight; nor has it any advantage in lubricating the parts: the packing of the glands is steeped in tallow and palm oil, which always preserve a greasy coat on the plunger, which the water, of course, does not remove. Wherever the climate is such as to endanger the freezing of the water in the buffers, then brine is the proper fluid, i, e., a saturated solution of common salt, which requires a very low temperature to freeze, and has no corrosive action on iron whatever, because it contains no combined air, as I have shown in another place. All oils get thick and viscous at moderately low temperatures, say 35° Fahr. In conclusion, while I am conscious of having bestowed some care and thought upon the subject of these buffers, and therefore have not advanced crudities capable of immediate or obvious amelioration, still I am equally conscious that no new method was ever made perfect but by repeated trials, practice, and emendations. The principle I have submitted to the public, together with the best modes I at present know of carrying it out; and no one will be better pleased to see them improved, than, Sir, your obedient servant, ON THE ROBERT MAllet. MANAGEMENT OF FURNACES SIR,-In my last communication, I al- 215 own eyes, and judge by the light of their own common sense-most of the absurdities of the present day would long since have passed into oblivion. Having however no other guide but the dicta of in ventors, and seeing how utterly we are without the means of detecting the chemical or practical errors on which inventions are frequently based; the boldest assertor too often obtains the most encouragement, while he is himself, perhaps, deceived by occasional success, the result of causes over which he had no control, or of which, perhaps, he had no conception. Under these circumstances, many plans which proceed on wholly erroneous principles, continue to be pressed on the unsuspecting public, while others, possessing real merit, are rejected, from the want of suitable means for estimating their qualifications. In the absence of internal inspection and observation, no plan should be sanctioned as efficient, or rejected as unsound; seeing how the supposed merit of the one may be dependent on unascertained, unsuspected, or partial causes, while the supposed defect of the other, may be the result of accident, omission, or local circumstances all of which, however, would have been instantly detected had suitable means of inspection been afforded. Of these, I will hereafter give some illustrations. At present, we have no test of the working of any "smoke-burning" expedient, but the appearance or disappearance of the black cloud at the top of the chimney; yet this absence of visible smoke, may really be the result of injudicious and even wasteful expedients, or the passing off of the combustible matter in an invisible, rather than a visible form. For as to drawing any correct inferences from occasional results, while we are yet unable to ascertain or determine the causes which produce them, it is but a species of self-deception, in which we would most likely be setting down to principle, what, if we had the means of judging correctly, would be found attributable to merely local or accidental causes. Thus, we are often unconsciously the means of perpetuating error and fallacy; and hence, also, the discrepancy between the results attributed, by different ex perimenters, to one and the same plan or process. |