In embanking, would it not, in many situations, facilitate the business to carry on in advance of the earth-work a wall for each rail; or, still better, a wall wide enough for both, of the whole height of the embankment, cemented for a few courses at the top. The materials could, in many situations, be had almost as cheaply as earth, and are of such kind, and may be used in such modes, as would allow the work to proceed at many points at once, an advantage of no trifling moment in works of magnitude. Much, too, of the subsequent settling, so injurious both to the road and the carriages, would be avoided. My principal reason for troubling you, sir, with these observations, is to request the attention of your correspondents to the project. Of the numerous mechanicians and engineers who will see them in your pages, there are doubtless some who can, and will, favour myself and the public with their opinions on the subject. If the plan is altogether impracticable for any reason whatever, it would certainly be performing a public service to prevent capital and attention being wasted upon it. If it be so capable of improvement as to have a chance of being brought into operation, it will probably much facilitate the adoption of that wonder-working invention the railroad—to point out the errors of the foregoing suggestions, and the alterations necessary to success. I am, Sir, Yours with great respect, Feb. 9, 1836. A PROMOTER OF RAILWAYS. [Since receiving the above, we have been informed that a continuous stone railroad has been adopted, in several instances, in America. From the experience there acquired, it appears that when the iron bands are laid immediately on the stone, considerable wear takes place; but that this is entirely prevented by in. terposing a strip of wood 12 inch thick. The plan of fastening (in which much of the difficulty seems to lie), is to insert a plug of wood in the stone, and drive home into it a square spike of such a size that its corners should touch the circumference of the hole in the stone. The dimensions of the iron-band, proposed in the above letter, seem to be sufficient for a velocity of sixteen or twenty miles per hour; but on the New Orleans and Nashville Railroad (Mr. Ranney, the very intelligent chief engineer of which, is now in this country), it is intended to use a band 3 inches wide by 1 inch or ths thick, and the tracks are to be 5 feet wide. This road is intended to bear a velocity of 60 miles per hour; and Mr. Stephenson has actually contracted to supply an engine, which will perform this with a load of 200 tons!-ED. M.M.] IMPROVED METHOD OF BLASTING ROCKS. Have any improvements been recently made in the mode of applying gunpowder to blasting in Cornwall?—Yes; think two or three important ones. Have the goodness to describe the former practice and the present?-The blowing rock by gunpowder is a simple process; the hole is bored into the rock, and in such direction as to expose the weakest part to the action of the powder; this hole is charged with a certain portion of gunpowder, and is then filled by clay, or more usually with a soft kind of rock, which is rammed into it, leaving a small orifice through which the rush or fuze is afterwards introduced for setting fire to it. The most dangerous part of this process is the ramming in of this soft rock to confine the powder, which is technically called tamping; this used to be done with an iron bar; that bar striking siliceous portions of the rock, inflamed the powder, and the men were injured, perhaps killed. The first improvement was making that bar of copper, or a part of it of copper; still the needle or small rod which is introduced in the tamping, to preserve the orifice for blasting, was of iron, and that sometimes inflamed the gunpowder : some years ago we substituted copper instead of iron, and in doing so had very great difficulty with the men; it was one of the strangest things possible to see the masters and the agents taking all possible pains to preserve the men's lives, and to find the men so reckless, that though those copper needles were given to them at the same cost only as the iron ones, they would not for a long time use them. I believe we prevailed at last by depriving all the men who were injured in that way of the relief which is usually given from a fund raised in the mine; and I be lieve that was more effectual than any thing else that was attempted, though we tried fines and many other expedients. That copper needle is now generally used, which is the second improvement that has been introduced; but I think the last improvement is one of the best; it is the invention of a person in Cornwall, who has made what he calls safety fuzes, instead of the usual practice of filling a rush or tube with powder and dropping it into the hole; this person has invented a cord, in which is introduced a thin vein of gunpowder, and is covered with tar or pitch; and the safety this gives is owing to a certain length burning in a certain time. Accidents took place frequently to the man who had to fire the hole; for instance, in sinking at the bottom of the shaft, the workman has to fire the hole, and then to be drawn up by a single rope over it; if the fuze communicate to the gunpowder more rapidly than he expects, he is blown to pieces; but with the safety-fuze he may take two feet or three feet, and so delay the explosion that he may be sure to be in a place of safety before it happens. This is made so cheaply, that no difficulty has been found in its introduction; the men are supplied with it, so that it is not worth their while to make the common fuzes, and I think it is one of the most happy thoughts that has occurred. HUTCHISON'S AND TAIT'S GASOMETERS. Sir,-You favoured me by publishing in your Journal of January 30th iny description of Hutchison's gasometer; I have now to beg your insertion of the following reply to a letter, signed “W. Tait," which appeared in your last Number. We are referred by that gentleman to an article in the London Journal of Arts, for June, 1824, describing a gasometer, which he represents to be "exactly similar in all its essentials to that claimed by Stephen Hutchison." I have examined Tait's gasometer, and must declare, that the two inventions (viz. Hutchison's and Tait's) are essentially different. They disagree in their most important and material features. The defects of the one are so remarkable, that though abundantly tried, it could never be brought into use; while Hutchison's gasometer proved one of the most economical reservoirs for gas that has yet been adopted. It is therefore extremely improbable, that the latter gentleman will ever disturb that priority of right which Mr. Tait charges him with having claimed. The principle of Mr. Tait's gasometer has been known for many years; Hutchison's is a recent invention, not yet four years old. The one was found to be so completely impracticable, that it was never considered necessary to secure an individual right by the purchase of a patent; while the other has been deemed worthy of that expensive security; and so advantageous has it proved to the enterprising company that first adopted it, that the other principal gas establishments of the metropolis have adopted Hutchison's invention into their works. The improvement is also becoming ge nerally known in the country, and gasometers on his plan are now erecting on the continent. If, therefore, Tait's and Hutchison's gasometers are upon one and the same principle, how does it come to pass, that the first-named gentleman's plan, although universally known for thirteen years, is no where in use at the present time-considering, especially, that par ties who were desirous of trying the experiment, were not prevented from doing so by any legal impediment? I am aware that Mr. Tait did exert himself with most creditable persever ance to induce gas companies, both in town and country, to adopt his suggestion; but I know, also, that though he succeeded in having a trial made, he suffered the pain of witnessing its complete failure. Therefore, to use that gentleman's own words:-"If there be any merit in the invention," he (Mr. Tait) is undoubtedly entitled to all the advantage which have or may result from it. I see by a document now before me in that gentleman's hand-writing, "that his gasometer had been tried at Leeds previous to his public announcement in June, 1824." Now if a gasometer upon his plan were ever in use in that town, its services must have been dispensed with many years since, as no apparatus of this description is now employed there. Very recently the new Leeds Company erected three gasometers upon the usual plan; and the old company, within the last four years, built a gasometer of large dimensions also upon the common method. Here are corroborative proofs, not only of Tait's gasometer being discarded, but that four years ago Stephen Hutchison's invention was unknown. Had the Leeds Companies been acquainted with this invention, no doubt they would have adopted it; and the old Companies could have converted all their old gasometers into the "double-lifting" principle, at less expense than was incurred, by the exertion of the single gasometer just alluded to. "In the works which I erected," Mr. Tait writes, "I introduced," &c. Where Were his gasometers are those works? then and there erected? If so, are they now to be seen in actual operation, or have they been for ever abandoned? pause for a reply. I If Mr. T. desires, it, I will inform him of several places where he can see Hutchison's plan in constant use. Mr. Tait labours under a delusion, if he is sincere in believing himself to be the originator of the telescopic gasometer. Neither can Stephen Hutchison establish a claim to priority of invention in respect to it. Let me inform both these gentlemen, that more than sixteen years ago a gasometer was erected upon this principle, invented by Mr. Hurst, of Leeds. It did not succeed, and was immediately abandoned. Also in June, 1818, a Mr. Stratton took out a patent for a gasometer constructed upon the same principle. Several were built under the directions of this gentleman by the Chartered Company, and after an enormous sacrifice of capital, they were found to be useless. To go even still further back-in the year 1802 Winsor, in conjunction with Joseph Hutchison, was pursuing a series of experiments upon the effects of coal gas at the house of a retired coach-master, of the name of M'Kenzie, in Green-street, Grosvenor-square. The retort used by these gentlemen contained upwards of thirteen bushels of coals; and as the gas used in the experiments proceeded directly from this retort, Hutchison was justly apprehensive of the occurrence of accidents from an undue pressure on the apparatus, and being a man of great mechanical knowledge, he attached a tube (resembling in appearance a syphon,) to the upper part of the retort; the other extremity being placed in a common pail, in which was water about fifteen inches deep. By this simple contrivance, all harm likely to result from a sudden pressure of gas was effectually obviated. Hitherto, Winsor and his coadjutor, Hutchison, had been conducting those experiments at their own risk and expense; but about the year 1805, a committee of seven gentlemen subscribed 100 guineas each to enable the above individuals to arrive at such a degree of certainty, with regard to the practicability of applying gas to useful purposes, as would justify them in the forming a company for the lighting of the public streets. During one of the meetings of this committee, which was held at the Star and Garter, in Pall-Mall, Joseph Hutchison, for the purpose of showing what could be done with gas, introduced a reading-lamp with a water-tube; by means of which the burner might be raised or lowered at pleasure. This was the origin of the hydraulic joint-one of the most useful contriv. ances which have yet been adopted in the manufacturing of gas. It is employed in a hundred different ways, and to as many purposes. The various gasometers I have alluded to in the course of this letter, were constructed from a previous knowledge of the above invention. To the unskilful and unscientific application of this joint is to be attri buted the failure of Mr. Tait's plan ;and to its better adaptation, Stephen Hutchison owes a superiority and success of his invention. As Mr. Tait, it would appear, seems unconscious of the defects of his gasometer, I will take leave to point out a few of them. The hydraulic cups being attached to the inner margins of the cylinders, forming his gasometers, are necessarily placed beyond the reach of workmen, and from under the control of the attendants, in the event of an accident. This is so unwarrantable an oversight in a gentleman laying claim to the title of engineer, that I am amazed he should, after an experience of thirteen years, still persist in making a public display of the blunder. Let Mr. Tait imagine the situation of a Company who were depending upon any number of his gasometers for a supply of gas during a severe, or even an ordinary frost-no ingenuity could apply any means for breaking the ice which would certainly be formed by the water in each of the cups. The Baltic or the Scheldt are not more effectually sealed against navigation during the winter months, than would his gasometers be against all practicable use under such circumstances. Then with regard to the arrangement of the divisions. The placing of the larger cylinder over the smaller is an error which alone would render his appa ratus totally useless. Mr. Tait must surely be aware, that the continual vibration which his gasometers would be subjected to (during even a trifling current of air) would cause an incessant_and most inconvenient of the lights. It is probable that the superincumbent weight of the top cylinder would occasion a sudden and violent inclination of all the gasometers; the consequence of which would be their total destruction, and the Joss of every particle of gas contained in them. These are merely a few of the objections which might be urged against Mr. Tait's principle. I will refrain from unnecessarily oceupying further the valuable columns of your Magazine, and take my leave of the subject, by allowing Mr. Tait, the sole and undisputed merit of his notable invention. Sir, In reading your interesting and valuable miscellany, I have been much gratified and amused with the different articles on railways: it seems as though the scientific and mechanical world were all intent on the subject, for it appears to be calling forth all the learning of the one and the ingenuity of the other; and it must be allowed to be a subject of such importance, that science and art cannot, at this time, be more usefully employed on any other. That there is and will be difference of opinion on the subject, is no more than is to be expected; but amidst all the plans and suggestions that are, or may be, advanced, the discriminating and skilful engineer will know what to choose and what to reject. The subject of rails and chairs has occupied some space in your Magazine, and my object in now writing to you is to call the attention of railway companies and engineers (particularly those of the continent of Europe and America), to a wrought-iron pedestal or chair, patented by Harry Scrivener, Esq., a gentleman connected with the British Iron Company. That a wrought-iron chair must be better than a cast-iron one, no one, 1 presume, will deny. Why else adopt the wrought-iron rail in preference to the cast-iron one? It cannot be simply owing to its extra length, and, consequently, causing fewer joints in a railway. The superiority of wrought-iron chairs to cast ones, must be, to say the least, in proportion, as wrought-iron is superior to cast-iron. What the comparative strength of cast and wrought-iron is, I cannot exactly say, as it differs according to the quality. But suppose a wrought-iron chair of 10lbs. weight to be equal in strength to a cast-iron one 20lbs., and the cost to be the same in the manufacture, the advantage to the purchaser is one-half in the conveying of chairs from the ironworks to the place of destination; so that if a double railway one hundred miles in length take, in cast-iron chairs of 20lbs. each, 6,775 tons, it will take, in wroughtiron chairs of 10lbs. each, but 3,387 tons 10 cwt; which is such a saving in carriage, as one would think would not be lost sight of—especially by the purchaser for the foreign market. Another advantage of the wrought-iron chair to the cast-iron one is its durability. As the oxydizing influence of the atmosphere is not so great on wrought-iron as cast-iron, the durability of the one, compared with that of the other, must be in the ratio of corrosive liability. Now, sir, as utility and economy must always be two leading considerations in all railway undertakings, the wroughtiron chair must, in point of saving, alone have ample recommendation. Yours truly, A SUBSCRIBER. WORKING OF THE NEW PATENT LAW AMENDMENT ACT. (From a Correspondent.) The provisions of this precious specimen of legislation, have been again brought into discussion before the Judicial Committee of the Privy Council, and another blunder discovered in it. Baron Heurteloupe applied a few days since to have a patent confirmed under Sec. 2. No action had been brought, and verdict obtained against him; but he admitted, that an invention, similar in principle, was known and patented in France some years before the date of his patent in this country. His application was not even opposed, but the Judicial Committee ex-. pressed very great doubt, whether, as the principle was not published in England before the date of the Baron's patent, they had jurisdiction, under the Act, to confirm such a patent. The words are-" if the patentee 'shall discover that some other person had, unknown to such patentee, invented or used 416 the same before the date of such Letters Patent." It was admitted on all hands, that this must mean invented or used in England. The further hearing was kindly postponed by 'the Judicial Committee till the 5th March, to enable the Baron to obtain an affidavit (if he can) to prove that the French principle was published in England, in some manner or other, prior to the date of his patent; so that the patentee is called upon to impeach his own patent, in order to get it confirmed; or, in other words, to kill himself, that he may be again resuscitated by this new patent principle of legislation. Lord Lyndhurst distinctly said, "This Act must be amended." We hope his lordship will set about it in good earnest,-there is no person better qua:lified to take it in hand. NOTES AND NOTICES. ·Electrical Theory of the Universe.-The gentleman who called at the office of the Mechanics' Magazine, in reference to a proposal for delivering -lectures on this subject, is informed, that Mr. Mackintosh has left his address at the office, and that he will be happy to communicate with him relative to the object of his inquiry. London Fire-Engine Establishment.-We are informed by a correspondent, that during the last week the Licensed Victuallers Fire Assurance Company have joined this establishment; so that there is now only one Insurance Company (the County) which has not given its adherence to the brigade. We trust this independent course will not be long continued. Extensibility of Gold, Silver, and Platina.-The hundred-thousandth part of a grain of gold may be seen by the naked eye; and a cube of gold whose side is but the hundredth part of an inch, has 2,433,000,000 of visible parts. A cylinder of silver covered with gold leaf may be drawn out 350 miles Gold leaf can long, and yet the gold will cover it. be reduced to the three hundred thousandth part of an inch; and gilding to the millionth. Silver leaf can be reduced to the hundred and seventy thousandth. The specific gravities are 193 to 105. Lace-gi ding is the millionth of an inch thick; gold Platina wire leaf the two hundred thousandth. may be the fifty thousandth of an inch; 500 inches of gold-wire has been drawn from a grain. Tinfoil is the one thousandth of an inch, that is, 200 gold leaves are only equal in thickness to one of tin-foil. One grain of gold will cover 7 inches each way, or 52 square inches, or be 1,500 times thinner than writing-paper, that is, a sheet of writing-paper would be 1,500 leaves. A 200-Scavenger Power.-M. Bernel, an engineer at Lyons, has invented a machine, which, worked by one horse, collects and throws into a cart, in a given time, as much mud as could be collected by 200 scavengers. Important to Bakers.-A mechanical kneading. trough has lately been invented by a baker of the mame of M. Fontaine, at Paris, for which he has obtained a patent from the French Government. The chief advantages derived from this new invenion are, that from 30 to 800lbs. of dough can be kneaded in the small space of 15 minutes, with the labour of only one man, and that without the least fatigue. It also causes the dough to be much bett er kneaded, consequently the bread is much made than by the process usually adopted. bette The in vention is the fruit of long experience, Railway Tunnels.-At the last meeting of the Institute of Civil Engineers, a communication was read from Mr. George Smith, engineer to the Leeds and Selby Railway, on the ventilation of tunnels on railways, whose experience has been founded on the construction of the first in this country, of half a mile in length, at the entrance from Leeds. Although, after the passage of a carriage, the tunnel appears to be filled with smoke and steam, it becomes perfectly clear within five minutes afterwards-the time, however, depending upon the state of the atmosphere and the wind. No inconvenience, likewise, is felt by passengers in their respiration-a free circulation of air always taking place through the shafts. "A late Member" is evidently very imperfectly acquainted with the bearings of the answer given by Mr. Toplis respecting the London Mechanics' In. stitution. We by no means agree with a "Se. ceded Member" in all he has said on this subject; but neither his statements nor arguments are ma terially affected by the letter of our present correspondent. If A Looker-on" will furnish as with a real name and address by which we can ascertain posi tively that he is not Mr. Herapath, but "a different person, resident in a different country," we will publish his letter. But, with our present impresWhen we reflect sions, we must decline doing so. that in the letter of "A Looker-on" Mr. Herapath is represented to be the only mathematician in existence who could solve a certain problem, we cannot help being of the same opinion as our esteemed and venerable friend, Iver M'Iver, that this "Lookeron" must be " aut Herapathius, aut Diabolus." We never said what "Galwigiensis" accuses us of saying, and challenge him to make good his assertion by proofs. All that "Hard Rub" states respecting the "India-rubber case," or rather India non-rubber case (because in this case the chief merit consists in the dissolving and incorporating of the India-rubber) may be very true, and yet Messrs. Macintosh, Hancock, and Co. be most unjustly and unhandsomely treated. Can any one deny that it is wholly owing to these parties that the caoutchouc manufacture is now so fast rising into magnitude and importance? Or any liberal and impartial person dispute that they are entitled to all the advantage they can derive from the exclusive enjoyment of their patent for a limited period? The injustice-such as there is in the case-does not consist in "certain parties" securing to themselves a "monopoly of a cer tain manufacture" (for a few years), but in other parties insisting upon participating with them on equal terms in the benefit of a manufacture, which but for the former parties might never have had an existence.-There's the rub. Patents taken out with economy and spatch; Specifications, Disclaimers, and Ame ments, prepared or revised; Caveats entered; & generally every Branch of Patent Business prom ly transacted. Drawings of Machinery also ex cuted by skilful assistants, on the shortest notice. The Supplement to the last volume, containin title, index, &c. and portrait of Charle Vignoles Esq., C. E., is just published, price 6d. Also, th volume complete, in boards, price 9s. 6d. LONDON: Published by J. CUNNINGHAM, a the Mechanics' Magazine Office, No. 6, Peterbo rough-court, between 135 and 136, Fleet-street Agent for the American Edition, Mr. O. RICH. 12, Red Lion-square. Sold by G. G. BENNIS 55, Rue Neuve, Saint Augustin, Paris. CUNNINGHAM and SALMON, Printers, Fleet-street. |