7 BEAUME'S AREOMETER. Can any of the correspondents of the "Mechanics' Magazine" give me directions for constructing Beaumé's Areometer correctly, and an accurate table of the degrees of the instrument and the corre sponding specific gravities. It is an instrument constantly referred to in French chemical works; and the tables in English books are far from satisfactory. How are the two tables in "Thenard's Traité de Chimie, Vol. II.," to be reconciled? It is strange that there is no account of this areometer in Dr. Brewster's scientific Encyclopedia. WATER-POWER. M. INQUIRIES ANSWERED, (See pages 111 and 112.). Filling of Syphons.-Sir,-If your * correspondent, W. J. will refer to Mechanics' Magazine," vol. i. p. 332, he will there find what I consider an excellent method of filling syphons. By *2 means of the arrangement there pro complained of, and will also enable W.J to dispense with the more delicate an expensive machine-the air-pump. Snapping of Pumps.-With respec to the next inquiry, I may observe, that at p. 252 of vol. viii. I stated it to be my opinion, "that the velocity of a fluid 'rising up a tube in vacuo, diminishes in proportion as it approaches that point at which it is in equilibrium with the atmospheric pressure ;" and subsequent reasoning and observation have confirmed me in this opinion. In all pumps that I have met with, whose height amounted to or exceeded twenty-eight feet, the effect noticed by your correspondent invariably occurs, in some more than in others, according to circumstances. To illustrate the above statement, let us observe what takes place in a pump, the feed pipe of which we will suppose to be thirty feet high. When the pump is first worked, it raises the air out of the feed pipe, tending to pro duce a vacuum; into this vacuum the water rushes, with a velocity proportionable to the force of atmospheric pressure; which in round numbers may be stated at fifteen pounds per square inch. But by the time the water has risen ten feet in the feed pipe, the pressure of the atmosphere, and consequently the velocity of the water, will be nearly onethird less than on its first entrance: that is, the ten feet column of water in the feed-pipe will be equal to one third of the atmospheric pressure, or five pounds per inch. The water will therefore be forced up above this distance, with a force equal oply to ten pounds per inch. Again, when the water has risen twenty feet, it will be impelled with a diminished force of five pounds only per inch; and by the time the water reaches the valve at the bottom of the pump-barrel, its velocity will be but trifling, the impelling force being reduced to about one or two pounds per square inch. It follows, therefore, that in working pumps of the height of twenty-eight feet and upward, a slow motion of the handle is absolutely necessary; because, if the piston is suddenly raised, a vacuum is instantly formed in the pump-barrel, which cannot be so quickly filled up, on account of the smallness of the atmospheric pressure, which is not sufficient to overcome the vis inertia, friction, &c. of the water in the feed-pipe, and give it such an increased velocity as will enable it to keep pace with the rapid motion of the piston. This being the case, therefore, the FERRY BOATS-BRASS TUBING. posed, the syphon may be filled by a water pump at the top of the shaft; which will obviate some of the difficulties piston descends before the pump-barrel is filled, and the lower valve, which was kept open by the entering water, is suddenly shut, causing an unpleasant snapping noise. Or should the piston be prevented from descending until the barrel is filled, that circumstance is announced by a similar noise. If the feed-pipe of any pump is made too small, the labour required to work it is greatly increased, and much inconvenience arises; but when a pump is twenty-eight or thirty feet above the level of supply, the effect of progressive retardation, described above, will be greatly increased by a contracted feed-pipe. In pumps of small heights, if the feed pipe is in reasonable proportion, the water follows the piston so closely as not to mar its easy and quiet action. It is stated that the diameter of the feed-pipe is best proportioned, when it is from two thirds to three fourths of that of the workingbarrel; and although attention to this particular will always mitigate, yet it can never entirely remove, the evil complained of by your inquiring correspondent. A table of the proportion of pumps, according to the height of water to be raised, will lo found in "Ferguson's Lectures," and also in "Nicholson's Operative Mechanic;" where, by the bye, it is erroneously attributed to Mr. Ferguson, whereas that gentleman gives it as the calculation of Mr. Booth; in this table, however, the proportion for the feed-pipe is omitted.. -I am, &c. Wm. Baddeley, jun. Joining Tinfoil to Paper.-Sir,-In answer to F. L. M.'s inquiry, I beg to observe, that I have for many years adopted the following mode of applying tinfoil to my Leyden jars, to prevent their breaking, from the high power I generally employ. I wash the tinfoil with a solution of pearl-ash, to detach the grease which is left on the surface after rolling, and make my paste with aluminous water, similar to what shoemakers make use of, with which I paste the foil on paper, and that on the glassthe tinfoil adheres so strongly to the paper, that it cannot be detached without considerable force.-I am Sir, Yours, &c. C. Wilkinson. Bath Mechanics' Institution, April 1, 1829. [Another correspondent, "T. E.," offers to make "F. L. M." “acquainted 159 with the secret," on " "knowing his address;" but after the above obliging communication from the learned President of the Bath Mechanics' Institution, we do not suppose there will be any secret in the case worth knowingEDIT.] Ferry-boats.-Sir,-In answer to the inquiry of your correspondent, "T.S.N.” I beg to observe, that the river between Norwich and Yarmouth is, I believe, about the width he mentions; across which there are three ferries, viz.Swilingham, Buckenham, and Reedham ; The boats which ply across this river are in the form of a paralelogram, the length being to the breadth nearly as 3 to 2, and flat-bottomed; for the conveyance of cattle, carts, waggons, &c. The sides of the boats rise a little above its surface, which is concave, or lowest in the centre. There are four or five upright timbers placed on each side of the boats, through the heads of which there are irons fixed, to prevent the rope by which the boats are drawn across the river, from slipping over the timber beads. There are two strong posts placed on the landing-placé, on each side of the river, to one of which, on each side the river, the rope is fastened, for the purpose of drawing the boats over. The rope is sufficiently long to drop to the bottom of the river; and is no preventive to the pessing and repassing of keels, wherries, &c. The rope is placed between the timbers, on the boat side, as occasion may require ; and the boat drawn across by a man taking hold of the rope, and drawing it through his hands; or, otherwise, by his taking hold of the rope, and walking from one end of the boat to the other, without letting the rope slip through his hands; which process must be repeated till be gets across the river. There are short ropes fixed on each of the four posts, for securing the boat to the landing-place, by fixing them over the timber heads, at the corners of the boat. If there were two posts only on the side of the boat, and the rope was made to pass through the timber heads by means of friction rollers, it would probably be an improvement.-I am, Sir, Yours, &c. J. Utting. Brass Tubing.-Sir,-I should recommend "A Juvenile Reader" to purchase drawn brass tubing, which he can have of almost any size. I have used it myself for models of pump work, &c. &c. cutting it to the required length, and $180 MISCELLANEOUS NOTICES. soft soldering a collar at top and bottom, and find it not only truer and better, but also incomparably cheaper than any bored cylinders of small diameters.—I am, Sir, Yours respectfully, Wm. Baddeley, jun. March 31st, 1829 MISCELLANEOUS NOTICES. New Stove. We extract the following notice from a French Journal:- Mr. Elsom, an Englishman, in Brussels, has just obtained a patent for a very elegant, yet simple piece of mechanism, consisting of a handsome polished steel stove, with a chimney formed of tubes, which slide one into the other, in the same manner as the joints of an opera glass. The stove can thus, with the greatest Pase, either be drawn into the centre of an apartment, or be moved, at pleasure, to any intermetiate space from thence to the aperture of the chimney. Hot air ventilators, which open and close at will, regulate the temperature of the room. This simple, yet ingenious invention, has riven great satisfaction to the higher classes of Brussels; and we shall shortly see none but Elsom Stoves in our fashionable saloons." To Measure the Heights of Buildings by Shadow-Make a mark at the extremity of the shadow, and measure a foot of the shadow; at which hold a walking-stick, or any other kind of rod of sufficient length to exceed the shadow; the extremity of the shadow on the rod will be in proportion to the foot measured; and the distance from the rod to the object to be ineasured must be calculated by this shaded part of the stick, which will show the number of feet the object is high.-Z. Bookbinding.-Roger Payne, the celebrated English bookbinder, ended a life of labour,poverty, and intemperance, in St. Martin's Lane, and was buried at the expense of his friend. Mr. Payne, the bookseller, though no relation. His workmanship was in a very superior style, and consequently procured him high prices; and the books bound by him continue to obtain large sums. For the binding of an Eschylus" for Lord Spencer, he received fifteen guineas. He was very singular in his conduct; he made all his own tools, and never would work before any persor, but always in some secluded cellar, and only when his necessitiés called upon him for exertion. Climbing Boy System-There has been one victim more to this atrocious and inhuman system. A boy named James Probert, between seven and eight years of age, was, on the 26th of last month, suffocated to death at Hereford, in a flue which he was sent up to clean. The jury which sat on the body of the poor child subjoined to a verdict of accidental death the following humane observations:-"They could not omit stating their opinion, that the use of children as climbing boys is pregnant with mischief to the helpless intividuals employed; is fraught with inhumanity and injustice; and calls loudly for the introduction of some substitute to do away with the necessity of employing children of tender age in the cleans ing of chimneys." lity of my bringing it into public notice by my own exertions. Its utility, and the certainty of its producing the desired effect is obvious, on inspection, so as to leave no manner of doubt,-that is, provided it be seen in action. Considering that every inventor has a just claim to partake in the profits of his inventions, and knowing the difficulty which exists of obtaining security in such cases against the designs and artifices of unprincipled men, my invention remains locked up in my own breast; but with this I am dissatisfied; and though I should never reap the least benefit from it, I would much rather communicate it. If, therefore, any public spirited gentleman, whose circumstances or known weight in society will enable him to patronize it with effect, and who (I must make it a proviso) shall be recommended by yourself, will apply to me, I will fully communicate it, and forego all claim whatever to any advantage arising from it. I send you, Sir, herewith, my real name and address --I am, &c. N N. N. Sir,- O. C. F." says he is not aware of any essential mistake in his valuable Table inserted in your 295th Number. I beg leave to point out to him, that he has counted all the w's and y's in the English language as consonants; whereas one fourth of the w's, and nine tenths of the y's, are Vowels. The numbers, corrected would stand nearly thus: "In the English Language, J. Brown, Jun. MINOR CORRESPONDENCE. Sir,-A considerable time since, I invented a.. machine calculated to be of great and general atility. My circumstances preclude the possibi Communications (post paid) to be addressed to Printed by G. Duckworth, 76, Fleet-street. Mechanics' Magazine, MUSEUM, REGISTER, JOURNAL, AND GAZETTE. No. 298.] SATURDAY, APRIL 25, 1829. (Price 3d. "What pleasure find we in life, to lock it up from action and adventure? ›› 162 NEW SYSTEM OF AER OSTATION. NEW SYSTEM OF AEROSTATION. BY S. R. When ingenious thoughts first enter the mind, by registering and reviewing them, they frequently prove to be capable of being realized, whereas at first appearance they look so visionary as not to be worth entertainment or further consideration. Although the subject of this paper has, with the writer, been only an amusing speculation, occupying his attention occasionally, it may, at no very distant period, become with many a matter of great interest; to the young and rising generation it most likely will. Unexceptionable pleasures cannot be too much multiplied for youth; by their enjoyment the relish for virtue is not diminished, but augmented. When we consider the great state of perfection that almost every branch of art has arrived at, it does appear extraordinary that the art of flying, or that of performing a free and easy passage through the air, with the aid of sails or wings, or other mechanical means, should never have been attained so completely as to render it available to the various useful purposes of life, which it is so eminently calculated to accomplish, at an extremely trifling expense compared with all other modes of conveyance. Perhaps the danger to which the practitioner has hitherto been continually exposed, by such insecure and inadequate means as have been provided, may help to account for the little progress that has been made in the art. Chimerical as the thing may appear at the first glance, there is, at least, more philosophy in considering that it may be possible, than in joining with those who, to show their own good sense and quick discernment, instantly pronounce judgment against a project of this sort, without condescending Jo spend one moment's thought in weighing the chances of its success. The writer hopes to be able to show that the problem may with safety be solved, the more especially as the plan he has to propose will be grounded on the absolute necessity of securing to the adventurer, while acquiring the rudiments of the art, the power of delivering himself gently and safely on the surface of the earth, under every circumstance of stormy winds and dead calms. Indeed, without first acquiring that power, nothing ought to be attempted; and a learner should be strictly prohibited from practising any other parts of the art, until he is fully master of this preliminary acquirement, though he should find it necessary to devote years to the service, before he may be permitted to taste the delightful and invigorating sensations that must undoubtedly be excited by, and accompany a rapid, safe, and easy passage through the elevated regions of the air. even The aërial carriage of "W. C." (since stated to be the late Sir William Congreve), inserted in the "Mech. Mag.," in March, 1828, was an excellent invention; and though it did not appear till long after the fundamental parts of the present system were written, it is probable something like his plan will be acted upon at a future time, in the way that steam navigation succeeded that of common or natural sailing. The utility of the art will not be disputed even by men of the most limited views, when it will appear, that by sailing with a fair wind, at the moderate rate of thirty miles an bour, the aeronaut, or, if I may be allowed to coin a word for the occasion, the airiner,-may, in one day of fifteen hours, breakfast at London, dine at York or Newcastle, and sup at Edinburgh; performing a voyage of four hundred miles. But this is little to what the art will enable us to accomplish. Men will, when once master of it, explore unknown regions-penetrate to the interior of continents—pass, in the cool salubrious breeze, over inaccessible forests-traverse the deserts of Arabia and Africa, without having to endure the concentrated heat of tropical climes, which will only exist, innocuous, miles below him. To the collections of the na |