MR. HENSON'S AERIAL STEAM-CARRIAGE. the north, which if reached, would materially improve her prospect of success. In the event of the ice closing, the propeller could be instantly drawn up into the body of the vessel, and when wanted could be as expeditiously replaced, especially as smooth water generally prevails between the floes of ice. In case of frost, the screw is wholly under water, and entirely free from that accumulation of ice, which would take place about the paddle floats and boxes of an ordinary steam-vessel, to the great detriment, if not the entire destruction, of the wheel. Should the vessel be caught, and compelled to winter, a steam apparatus for warming the vessel throughout could be fitted with little trouble. And as the propeller is only intended to be used as an auxiliary power, a small high-pressure engine would be all that would be required, and consequently it would take up but little of the stowage of the vessel. In short, it seems as if this invention had appeared about this time to stimulate us to further exertion, and the auspicious return of Captain James Ross from the Antarctic seas, with officers and seamen already accustomed to the ice, and with two vessels ready strengthened, to which the propellers could be applied at a moderate expense, appears to mark the present as a period at which arctic research might be advantageously resumed." ON THE OBJECTIONS TO MR. HENSON'S PLAN OF AERIAL TRANSIT. BY L. L. (Concluded from p. 318.) I formerly noticed the dearth of needful experiments, and utter absence of sufficient theory on this subject. It is probable, however, that the experiments mentioned by Sir George Cayley would supply some important data. It has not been iny good fortune to meet with any account of them, and perhaps they are not published. Does it follow, that, because a crow, stationary in the air, with outstretched wings, would acquire, in falling through the air, a maximum velocity of 21 feet per second, that he must lift himself with his wings at that rate? Suppose the beats be made at the rate of two in a second, at the end of the first half second, the velocity acquired is less than the half of 21 feet; it is destroyed, and the original position regained by the first stroke of the wings. The next, and every succeeding half-second, is but a repetition of the first. Perhaps enough is said to show that this principle of calculation needs to be revised. 337 It is suggested that, if the wings of Mr. Henson's machine were inclined to each other, like a V, the stability of the whole would be increased. It will, however, be observed, that, as at present constructed, the centre of gravity is at some distance below the wings, sufficiently so, perhaps, to ensure the necessary steadiness, and that too stable a machine, that is, one which would yield but little to the blow of a gust on one end, would be in danger of being broken by the blow it may be, on the whole, safer if it suffer itself to be rocked to some extent by such an impulse, provided the effect of the weight below the planes is sufficient to ensure its gradual return to a steady horizontal position. It is probable that this is one of the points which only experience can determine. : Of perhaps more obvious utility and more probable adoption is the plan of dividing each wing into two or more portions and placing them over each other. The danger here, I conceive, is that the air between the "decks" would not act with the same effect as if it were not so confined. Here again, we have no certain facts for guidance. Sir George seems to conclude, that Mr. Henson's speed will be limited to that of the crow, or thereabouts, and I believe Mr. H. himself has made no great professions on this point. But it should be remembered, that a high speed will require but little more power than a lower one for its maintenance, if that high speed be communicated at starting by the inclined plane, or stationary engine. Connected with this subject are some conclusions of great importance, of which I can now mention only one. If a carriage on Mr. Henson's plan, with its wings at a certain angle with the horizon should be driven by greater power than is necessary just to maintain its speed, the whole machine will rise: to prevent that rise, the wings must be placed at a smaller angle, and at that smaller angle they meet with less forward resistance. The superabundant power must be spent in elevation or in speed: and the power and angle are so coupled together, as that to diminish one, requires an increase of the other, if the uniformity of the speed is to be preserved: and if the whole or any given part of the embarked power is to be employed, it may as well be spent on a high speed as a low one. All this, however, supposes the common theory of oblique resistance to be true, or at least, in this respect, to have the same consequences as the true one; and it supposes also, that we have to deal only with the wings, and not with the resistance of the air to the car, &c., &c. I adduce these consequences, subject as they are to reservations so large, merely for the sake of showing that it is not certain, or even probable, that the machine, if successful at all, will be limited in use to low speeds. In common with many others, Sir George fears that the wings are much too large to be made strong enough, and compares them with those of birds. Perhaps it is enough on this subject to say, that we build locomotives and ships much larger and stronger than horses and whales, and may therefore conclude with some likelihood, that in flying machines we may not have to stop at nature's limit of size and strength. Navigable balloons seem to be liable to two objections, besides those which have been commonly noticed. The first, is, that in passing with any useful rapidity through the air, their shape would be greatly altered by the pressure in front, and, therefore, the amount of resistance would vary greatly from that which might be anticipated from the original conformation. The other, and perhaps more formidable difficulty is the following:-if the propelling apparatus be entirely in the car, that appendage would be dragged considerably out of the perpendicular before the balloon would move with it, as will appear on consideration of the forces which must act in the case. I cannot see how this evil is to be obviated, but by mounting part of the propelling apparatus on the top of the balloon, or in some other way, so disposing of the parts which actually strike the air, as that the resultant of their pressures shall correspond in position with that of the pneumatic resistance. At present there seems little hope that this mode of aerial transit will be rendered available; but the registering and discussion of its principles, will either bring it into working condition, or at least tend to save us from loss and disappointment, which might for a long time discourage all attempts to accomplish the same object, however different might be the means. This paper, already too long, I must Sir, We are not destitute of data for estimating the force which is called into action in order to sustain, and keep in motion in the air, bodies, more or less heavy; sufficient has at least been done to enable us to form some conjecture respecting the probability of the success of Mr. Henson's machine. An elaborate memoir on this subject by M. Chabrier, has been published by the Institute of France, in which will be found a profound mathematical inquiry into the conditions necessary for the movement of machines in the air. In Dr. Todd's Cyclopædia of Anatomy and Physiology, part 23, article Motion, I have contributed a number of illustrations, by ascertaining the weight of various insects, bats, and birds, and the amount of surface in each respectively. I have also computed the number of strokes made in a second by the wings of the rook and the pigeon during flight. It appears that the average weight of the pigeon is 4347 344 grains; that of the rook 4170.25 grains; and that of the canary 229 grains; whilst the areas of their wings are respectively, 0.6198, 1.11, and 0·054 of a square foot. Hence we see that the areas of the wings of birds do not vary as their weight; and that the rook has nearly half a pound weight to the square foot, and the pigeon one pound; the former making two, the latter, three effective strokes of the wings in a second. The weight of the former is therefore greater, that of the latter less, in proportion to the surface presented to the wind than in Mr. Henson's machine. It must, however, be borne in mind that in this machine the surface presented to the wind has no motion like the wings of birds, neither does the machine possess the power of ascending vertically. In birds, on the contrary, according to MECHANICAL FLYING . NAVIGABLE BALLOONS. Borelli,* the power of the muscles which move the wings, compared with their weight, is more than 10,000 to 1; whilst their mass, compared with the muscles moving the legs is as 3 to 1. We agree with M. Chabrier, that the amount of force requisite for aerial progression is so enormous, owing to the rarity of the atmosphere, that it would be impossible for a man to sustain himself in the air by his muscular strength alone, in any manner in which he is capable of applying it. For example, it is calculated that a man can raise 13.25 lbs. avoirdupois to a height of 3.25 feet in a second, and that he can continue this exertion for eight hours in a day. In that space of time he will therefore exert a force capable of raising 381600 lbs. to a height of 3-25 feet, or 47700 lbs. to a height of 26 feet, which, according to M. Chabrier, is the height to which the swallow would raise itself in a second of time, by the force which it is obliged to exert in order to sustain itself in the air. Now, if we suppose the conditions necessary for flight in man to be the same as in birds; and that a man whose weight is 150 lbs., could concentrate the muscular power of a day's labour into as short a period as the accomplishment of the object required, the time t, during which he would be enabled to support himself in the air would be, 47700; hence, t = five minutes. 150 t 339 I have, however, elsewhere shown that I am, Sir, your obedient servant, London, April 15, 1843. MECHANICAL FLYING V. NAVIGABLE BAL- Sir,-Notwithstanding the tremendous "note of preparation" for an aerial trip to the antipodes, sober-minded philosophers persist in denouncing mechanical flying as a mechanical impossibility ! Perhaps few persons have studied this branch of science so thoroughly as your talented and respected correspondent, Sir George Cayley; and although he seems to admit that mechanical flying is of doubtful accomplishment, he is loth to give it up altogether. I quite agree with him in opinion, that "balloon navigation is that designed for the use of mankind." From pondering upon the principles originally laid down by Sir George Cayley, I was led to devise the navigable balloon, as announced in your pages and in several of the newspapers, nearly seven years ago, during which time it has been seen by several intelligent men, and by some of the first engineers of the day, who, however sceptical before, have, on inspection, one and all, declared that my plan is perfectly 318", or about practical, and would, if brought out, The surface of the wings in the rook and the pigeon when expanded, will not support them stationary in the air, unless they move with rapidity; for when the wings of the rook are expanded motionless in the air, the bird descends by its own gravity with considerable velocity; and as it has a greater surface, compared to its weight, than Mr. Henson's machine, it follows that the latter would be precipitated to the earth with still greater velocity, should the propelling apparatus get out of order in its transit through the air. It appears by M. Chabrier's analysis, that the quantity of force expended to keep a body, whose weight is W, stationary in the air, (all other conditions being supposed the same), is as W3 directly, and density of the air inversely. De Motu Animalium. 66 se cure to this country the glory of being the first to establish the navigation of the terrestrial atmosphere." My plan is still in abeyance, for I am getting somewhat tired of producing inventions for the gratuitous benefit of the million, and think it is now time that I should begin to reap some benefit for self. I must, therefore, be excused if I still withhold my long since perfected invention of a navigable balloon, until some more tangible benefit than the prospect of future immortality is forthcoming for my reward. The concluding sentence of Sir George Cayley's last letter, (page 278,) is worthy the consideration of every patriotic philosopher. Let his appeal be answered, and I prove that the hour is come, and the will man. I remain, Sir, yours respectfully, 29, Alfred-street, Islington. ADVENTURES OF AN AERONAUT IN SEARCH OF A PATRON. Sir, I wish, with your kind permission, to place upon record, in your valuable "Museum" of remarkable inventions, that, if the world is not already in possession of the art of flying, it is the world's fault alone, or at least that of the world's rulers. Some ten years and more are past since, after much thinking and contriving, I invented a machine wherewith a man may fly about through the air, at all heights, and at all times and seasons, with (almost) the same ease as he can walk or run. I did fly with it, myself; though, from the necessity of keeping the thing a secret, it was within doors, and in a chamber of not large dimensions. I first wrote to our own government, informing them of the discovery I had made, and offering, on terms, to disclose it, for the benefit and glory of the country. After the (too) usual routine of rebuffs, contumely, and importunity, I at last succeeded, through the intervention of the member for the borough of which I am a native, in obtaining an interview on the subject with Lord Melbourne, at his seat of Brocket Hall. His lordship received me with great affability, and heard, with the greatest attention, all I had to say. He then asked if I had my machine with me? I said, no; it was safe at home, under lock and key. "But," said his lordship, smiling, "if you won't take off the bushel measure, how can we be sure there is the light under it?" I was about to explain, that I was willing to exhibit the invention to any committee of scientific gentlemen the government might appoint for the purpose, on condition that, if they reported in its favour, I should receive a suitable reward; but his lordship, quickly resuming the discourse, thus continued "I'll tell you what I'll do for you, Sir: you shall come down here some day next week, and bring your machine with you; we shall start for town at the same time, you in your-what 'ye call it "No, and I in my pony phaeton, and if you reach Whitehall first, why then, Sir-I'll mention the thing to the Queen!” no, my lord," I replied, "I have lived too long in the world, and lost already too much, by depending on public gratitude for the reward of former inventions of mine, to make my present discovery known on any such terms. But if your lordship will engage that, should I reach Whitehall before you, the government will pay me 50,000l. down, and 50,000l. more after any period that may suit their convenience-that I would leave to themselves-then, my lord, it shall be a match, and may come off any day you like!" His lordship said, he did not know but what I was in the right; but that he could not, consistently with his public duty, make me any such promise. Besides, he did not know that, if we could fly, there would be any public advantage in it; people, as it was, were but too much given to mad flights. In short, he saw he could not do any thing for me, and was very sorry, &c. &c. As I was then about making my bow, Lord Melbourne added, in a facetious tone, "You should see Brougham, however he knows more about this sort of thing than I do." "I have seen Lord Brougham," I replied, "and it was he referred me to your lordship." "The deuce he did!" "Yes, my lord. 'You see Melbourne,' said he; 'yours is just the sort of thing he is in want of, to give him a lift—he will be delighted to see you.' At this Lord Melbourne laughed heartily, and, ringing his bell, bade me "good morning." Failing thus with the government of my own country, I applied to that of France, but had for my pains merely a polite acknowledgment of the receipt of my letter, and an intimation that “ they would not give me any trouble on the subject." I then memorialized the Emperor Nicholas, and was waited upon by one of his agents in this country, who asked me how I proposed to prevent the smuggling of goods, and escape of deserters across the frontiers of a country? The learned sovereign of Bavaria,-that especial patron of all the arts and sciencesdeclined my offers, on the ground that his dominions were of too small extent to make flying of any consequence to them; but promised that, if I succeeded, he would give my bust a place in his Walhalla. ("He asked for bread, and they gave him a stone.") The courts of Berlin, the Hague, and Vienna were next successively applied to, but all with no better success. And now, Sir, here I am, after going the round of Europe to obtain patrons for an invention which is not any matter of speculation, but one of absolute certainty, and second to none, of all that ever were invented, in importance, as unpatronized and unbefriended as when I started. Is it not, Sir, a shame that such things should be? I mean, in a few weeks, to pay brother Jonathan a visit, and see what he will say to it. Famous as he is for "going a-head," I have strong hopes that an invention which will enable him to "go aloft" as well, will be a little more favourably regarded by him than it has been by the dullards, (crowned and uncrowned,) of the old world. Could the young republic have any thing prouder to boast of-next to the achievement of its own independence-than that it INSTITUTION OF CIVIL ENGINEERS. adopted as its own an invention which, though unequalled in grandeur and importance, was rejected by all the world beside ? Just let me add, before concluding, that I have attentively considered Mr. Henson's scheme, and can confidently affirm that it is a complete delusion. I am familiar, also, with every other scheme of the sort which has been yet made public, and with several that have been only privately exhibited; but the more I have seen, and the more I see, the more thoroughly I am satisfied, that, if flying is ever accomplished-or, as I ought rather to say, if it ever come into general use, for, as I have said before, I have accomplished it-it will be by the machine invented by, Sir, Your most obedient servant, RICHARD EVERETT CHARNOCK. Thorn Cottage, Chiswick. April 12, 1843. PILBROW'S THEORY-IS THERE ANY Sir, I think you have acted with great (though perhaps pardonable) lenity, in 'letting off' your correspondent Duplex so easily. He verily and truly appears to believe in an innate power existing in motion-that is, that in a cannon ball in motion there is a selfborn power of motion, begot from its velocity alone. Why should matter in motion beget a power which, when at rest, it cannot beget? It comes to the old question-Hath matter innate motion? Certainly not-under no condition whatever, whether in motion or at rest. It is the "vis a tergo❞—the kick from behind-that projects matter, and when once projected, its motion is eternal, except from external causes, and when once at rest, its rest is eternal, except from external causes. I recollect its being stated before some persons, not without considerable pretensions to education and learning, that a bullet from a gun, shot upright into the air and supposed to fall down in the same straight line, would have, in falling, inch for inch inversely the same force or power that it had in rising; that is, that at a given distance from the mouth of the gun (say two feet) the bullet had a certain force; then, at the same distance in falling down, it would have the same force. This demonstrable fact was denied -probably by the family of "Duplex." Now, Mr. Editor, our friend "Duplex" having, in his opinion, abundance of proofs in support of Mr. Pilbrow's theory, rejects one (in his opinion again) crushing proof. He says, "not to insist on the analogy presented by falling bodies," &c. Not to insist, indeed! I think he dare not insist 341 REGULATION OF THE SPEED OF THE PISTONS AND VALVES OF LOCOMOTIVE ENGINES. Sir," Inventor," (No. 1019,) tells us that he can scarcely suppress a feeling of surprise that no practically good method has yet been adopted for diminishing the speed of the pistons and valves (of locomotive engines) without diminishing the speed of the engine itself;" and then recommends a trial of the sun-and-planet motion for that purpose. Without designing to call in question the utility of that ingenious and beautiful piece of mechanism, I beg to say that, during the course of last summer, I constructed a small model of a rotating appendage to the pistonrod, which will give any required number of revolutions to the driving-wheels, for each stroke of the piston, substituting for the varying force of the crank a power of uniform continuance. But whether mine may prove a "practically good" method, or not, is a question which a practical experiment on a working scale can alone determine. Nor can I pretend to say how soon such question will be resolved, having no practical knowledge of the arts necessary for its resolution. |