artists; yet, independently of my own conviction, I have had the testimony of some competent judges, ainongst others the late Messrs. Charles and William Tulley, to the remarkable excellence of the metals I have made. Perhaps the most valuable property in a metal, next to that of being capable of fine polish in the first instance, is that of retaining that polish for a long period unimpaired, even under atmospherical circumstances not the most favourable. This severe test will be well borne by metals cast according to the directions above laid down, as I have been used to leave my metals constantly in their tubes. undefended by any thing more than caps fitted to the ends of the tubes; and, moreover, have left them throughout the dampest seasons in outbuildings for years without their contracting any tarnish whatever, or indeed, any dulness of reflection which could be detected in vision with the telescopes. Nor have I ever had to re-polish a mirror solely on account of tarnish contracted. It is much to be regretted that the composition of the metals of the late Sir William Herschel, exquisite in figure as they inst have been, was very prone to tarnish, so much so as to render them sometimes, even at an early period, unfit for use. Even Sir John Herschel, now at the Cape, in a climate of which he almost speaks in raptures, states that he is obliged to have a change of metals for his 20-feet reflector, and frequently to repolish as their surfaces grow dull. In conclusion, it may be permitted me to mention what escaped me in its proper place that frequent re-melting of speculum metal is decidedly injurious to -it; and, therefore, all possible care should be taken to render the first casting successful. It may, however, be re-melted once or twice, adding an equal quantity of new, without apparent injury; but it generally requires a small extra proportion of tin to make the fracture flaky and briliant. Your most obedient servant, 18, Norton-street, Liverpool, A BOLD STROKE FOR A RAILWAY. Nothing daunted by their Parliamentary defeat of last year, the projectors of the rival lines of railway to Brighton are already in the field, and determined on another campaign. It is a pity they cannot agree to unite their forces, and thus save the expenditure of useless thousands, especially as they are now threatened with a new and formidable rival, in the person of Mr. Alexander Gordon, whilome editor of the Journal of Elemental Locomotion, and engineer in prospect to the "London and Holyhead Steam-coach and Road Company." This gentleman bas given notice in the Gazette of the intention to apply for an Act for the "improvement," in whole or in part, of the road from Brighton to London, by apply ing a new surface, for converting the same into a hard and solid road,—just the same thing, in fact, as was to have been done on the Holyhead Line, to make it fit for the running of steamcarriages; but this is not all,-Mr. Gor. don slily drags in such provisions as will enable him, if expedient, to convert the road into a regular railway. Thus be continues," and for making a tramway or ways, stoneway or ways, plateroad or roads of iron, stone, or other materials, for the passing of locomotive steamcarriages, &c. thereon;" all due powers are to be given to collect tolls and "to apportion the same between the present trustees and the persons authorised to improve the road," i. e. Mr. Gordon and his company! Messis. Stephenson, Cundy, Rennie, and Co. had better look to it forthwith, lest some fine morning in the coming session they find not only that their own bills are thrown out, but that Mr. Gordon, while apparently asking only for powers to improve a turnpike-road, has in reality obtained the Parliamentary sanction for a new line of railway. The road Mr. G. proposes to take under his special protection is that through Croydon, Ryegate, Crawley, and Cuckfield: he starts from the Elephant and Castle. MACKINTOSH'S ELECTRICAL THEORY REPLY TO NAUTILUS. Sir,-Upon reading the observations of your correspondent Nautilus, contained in 697 of the Mechanics' Magazine, it at first appeared to me that no answer was required to his animadversions. However, upon but few voyages of discovery in the ocean of abstract philosophy. Yours, &c. LONDON second thoughts, I am of opinion that it may be perhaps as well to say a few words with a view to the removal of any misunderstanding which may exist in his mind, or in the minds of others of your readers. Nautilus, in the article alluded to, is fighting a shadow. He might very well have spared his examples of the merry-go-round, the bottle of crusted port, and the small globe, in his endeavours to prove what no one denies, that all the particles of a revolving body do each of them revolve upon its own imaginary axis. I was not ignorant of this when I made the assertion that the moon does not revolve upon her axis, nor do I see any necessity to withdraw or qualify that assertion from what has been advanced by Nautilus. Kinclaven also objected to this assertion, but the parallel ease of the wheels and leaden balls at once enabled him to perceive that it had not been made unadvisedly. I have no intention of entering into any controversy with Nautilus upon the point I readily grant the correctness of his views with respect to the imaginary axis. His remarks upon the small machine bearing my name, and which, at the time it was first constructed, between thirteen and fourteen years ago, was expected to turn out a perpetuum mobile, require an answer even less than the former. It has been laying by me for upwards of thirteen years, and had I entertained all the father's fondness for the bantling, it would not have been suffered to lay so long neglected. I am fully satisfied that no perpetual motion will ever be effected, either with that machine or any other system of mechanical combinations that may be put together; when I sent it for publication in the Mechanics' Magazine, withheld an explanation of the cause of its failing to give a perpetual motion, under the impression that the ingenuity of some of its readers might be exercised in an attempt to discover it. The attempt of Nautilus is the first, and is a complete failure, I know well that the wheel will not, and I also know the reason why it will not go, but Nautilus has not yet made that discovery. In all that relates to declinations, right ascensions, latitude, and longitude, Nautilus appears to be in his proper element; but I am of opinion that he has made The rapid increase in the use of Indiarubber, or caoutchouc, as a material for the manufacture of various articles, has led to a speculation, having for its object the introduction of Mr. Sievier's patents to the public, under the title of the "London Caoutchouc Company." It has apparently met with a favourable reception, as the shares have been quoted in the market at a premium. To enable shareholders and others interested in the affair to form a just opinion of the utility of the inventions, the patent right of which, it appears, the Company are to purchase at a considerable expense, we now publish abstracts of the specifications of Mr. Sievier's three patents. The first patent, dated 1st December, 1831, is for "certain improvements in the making or manufacturing of cables, ropes, whale-fishing, and other lines; lathe and rigging bands; bags and purses; parts of which said improved articles are applicable to other useful purposes. This invention consists in the employment of filaments or threads, India-rubber, to manufacturing elastic cables, ropes, whale-fishing, and other lines, lathe and rigger bands, bags and purses; the threads of India-rubber being previously platted over or covered with hemp, flax, silk, wool, cotton, catgut, Indian grass, strips of leather, or other fit materials. The filaments or threads of caoutchouc are prepared by cutting them into long strips, which are afterwards stretched to their utmost tension, and wound upon drums, reels, or bobbins, ready to be platted over or covered by, or interwoven with, the various materials before-mentioned. This may be done by the machinery, generally used for making sash lines, braiding, platting, or stay-lace machines, or any other machinery of the like description. The threads being thus prepared by platting over, or intermixing them with any of the above-mentioned materials, and collapsing in their length to the degree of elasticity required, with out injuring their tenacity, are for the manufacture of the various articles before-mentioned. For cables, ropes, or other articles where great strength and elasticity is required, the threads may be passed through different machines, each machine taking a strand or cord of filaments, and platting or interweaving any number of filaments together, until there are sufficient for the required strength of the article intended to be made. For sash-lines, whale-fishing, or other lines, lathe, or rigger-bands, any required number of filaments are placed together longitudinally and covered with silk, &c., by a platting, knitting, or other machine. Lines made in this manner may be used as filaments to form cable-ropes, &c., either by placing them together longitudinally, and covering them with some material, knitted or platted, upon them; or they may be platted or interwoven together, as is before described of single threads, thus rendering an external casing unnecessary. When several large filaments are placed together to form cables, &c. by being woven round with hemp, &c. the interstices between them must be filled up with other suitable sized filaments. Bags and purses are made by knitting threads or filaments, prepared as before described, in the same way as purses, &c. are made of silk or other common thread, by machinery or by hand. Where elasticity is required, the bag or purse may be made wholly of the caoutchouc filament; as it may be only partially used, as in carpet travelling-bags, the ends or edges only of which should be made of the elastic material, covered, when stretched to its utmost, with leather, or other suitable substance; thus when empty, the leather, or other covering, will be drawn up into puckers or gathers; stretching when any extra articles are put into the bag. The second patent, dated January 17, 1833, is for "an improvement or improvements in the making or manufacturing of elastic goods or fabrics applicable to various useful purposes." Mr. Sievier describes this patent as having three objects; first, to manufacture an article by the ordinary knittingframe or similar kind of machinery, in which cords or strands of India-rubber shall be introduced between the loop ar stitches of the fabric, for forming elastic bands round the margins of stockings, socks, gloves, nightcaps, drawers, and various other articles of clothing, which he effects thus:-when the stocking, &c. has been made in the ordinary way up to the part at which the elastic band is to be placed by the adjusting screws of the machine, the lengths of the loops or stitches of the row next to be produced across the machine are elongated, or contracted, in order to form a channel to receive an elastic cord similar to that described in the first patent, or else a fine strip of India-rubber itself, which is conducted by a long needle, or other suitable apparatus, answering the purpose of a shuttle, across the machine between the row of stitches or loops which were last made, and those which are then about to be formed; the Indiarubber or elastic thread being drawn straight, the row of loops or stitches is completed, thus inclosing the Indiarubber or elastic thread securely in its place, interwoven with the threads of the fabric, and so on. The second object is to manufacture in the ordinary loom, an elastic woollen cloth, by the introduction of cords or strands of Indiarubber into both the warp and weft; which cloth may be afterwards felted and dressed with a nap. Either the warp or weft may be composed wholly or in part of the elastic cord; or the warp or the weft only may be made to contain the India-rubber; according as it may be desired, to produce a cloth, which shall be elastic lengthwise, or sidewise. Where India-rubber is introduced both into the warp and weft, it will of course be elastic in both directions. If cloth is to be produced with a nap upon its surface, yarns spun from short wool should be used with the Indiarubber, which, after having been woven, should be finished in the usual manner. The third object is to produce a cloth from cotton, flax, or other suitable material not capable of felting, interwoven with elastic cords or strands of Indiarubber, coated or wound round with a filamentous material. In each case the strands of India-rubber are, in the first instance, stretched to their utmost tension, and rendered non-elastic, and being in that state intro duced in the fabric, they acquire their elasticity by the application of heat afterwards. The third patent is dated February 7, 1836, and is for "An improvement in the means of dissolving and preparing caoutchous or India-rubber for various purposes." This patent is solely for the application of Ammonia to the dissolving of India-rubber. The following is the process which the patentee describes →→ I take caoutchouc or India-rubber cut into small pieces, and put them into any convenient vessel that may be closed at the mouth; I then fill the vessel with liquor ammonia, so as to entirely cover the Indiarubber in a few months it will be dissolved, or its particles separated; I then put the solution so made into a still or large retort, and by the application of heat, nearly the whole of the ammonia will be distilled over in a gaseous form, and is to be taken up in the usual way by cold water; in that state it again becomes liquor ammonia; in this operation of distillation I prefer using a water bath, as the India-rubber by that means cannot be subjected to a heat of more than 212° of Fahrenheit; the ammonia assumes a gaseous form at 130%. On separat ing the ammonia by distillation as above, the India-rubber is left held up in the water, and in that state may be applied for water-proofing cloths, or making solid masses of any form; by subjecting the solution to evaporation, any degree of consistency may be given to this solution by increasing or diminishing the quantity of water mixed with the previous dissolved India-rubber. * * * I claim as my discovery or invention the use or application of ammonia to effect the solution or separation in the manner herein described." MAKING SERAPHINE TONGUES-AND HINTS ON MUSICAL MECHANISM. Sir,-A" Mechanic" inquires in the Number of the Mechanics' Magazine for September, "What is the best metal for making the tongues of the seraphine ?" I have, in the course of several years, at different times, tried experiments with the view of solving the same question; and I have lately been induced to employ steel, which, upon examination, I found was used by several manufacturers of the instrument, and also by the makers of the Eolophone. The steel which I have used, and which fully answers my expectations, is the best treble shear steel, which I get very carefully and nicely forged, and hardened by cold hammering. I then make my tongues of the steel without tempering by heat, which would give much trouble in tuningsteel produces more of a trumpet-tone than brass-which tone may be subdued by having a small wooden box (with a sliding cover for voicing, &c. over each tongue, as in the Eolophone), if the tongues are placed on a wind-chest, or by mortices through the top board if they are within the wind-chest, as is the case with the seraphine; and it may be still further moderated by the addition of one or two swell-boxes" over the whole, which boxes may be well cushioned. Even with steel I fear your correspondent will occasionally have to complain of breakages. But if he fastens the tongues by screwing down upon them a small brass-plate bridge with two screws (as now adopted in the best instruments), he will find little trouble in fitting in new tongues; whereas, if he follow the old plan of fixing with a screw passing through the tongues themselves, much difficulty will be experienced in replacing and adjusting them. To preserve the tongues from rust, perhaps it would be as well, when finished, slightly to lacquer them, or, at all events, to pass over them an oiled rag. When I contrived my instrument (now between eight and nine years since), I derived my scale from one of the Eolians which a friend had just brought from Germany, and I employed brass for the tongues. They being short, and consequently thin, I was constantly annoyed by their breaking; but this defect the steel, I trust, has in a great measure remedied. Your correspondent, of course, is aware that in this particular much depends upon the weight of wind employed. The substitution of these reeds for organ-pipes appears to have been made by many individuals about the same time; and, indeed, the feasibility and desirableness of the thing would strike all who saw and heard the German Eolians when they were first introduced into this country. But I very much suspect that the invention is only the revival of an old one. In this I may be mistaken. My reasons for this sus picion are the following.-If your readers will refer to Brewster's Encyclopedia, art, Organ, they will at p. 674, meet with an extract from Biot's Traité de Physique, from which it appears that the same kind of reed, &c. was used by Mr. Grenié in organs-with this difference, indeed, that they were enclosed in sockets, and had hollow hemispheres above them to give fullness to the tone; a construction of reed stop, which, from the many advantages attending it, one would have thought would have become general. At the It is somewhat singular that the very same form of reed was tried by myself and my esteemed friend, Dr. Camidge, in 1819 or 1820, with the view of introducing it into the York Minster organ, which was then being enlarged. time when we employed this kind of reed we had no knowledge of what others had done; and the hint was derived from that very unmusical instrument, the Jew's harp. However, the plan was abandoned on this account; notwithstanding that the organ-builder had taken every pains in forming the reed, tongue, and pipe; and although the tone produced was of excellent quality, yet, either from a fault in the tongue or false proportion in the pipe, the flat seventh was produced so strongly with the proper note, that it was unbearable. No further experiments were tried by us, and the contrivance fell to the ground. Perhaps some of your correspondents can inform me whether the Regal, which Dr. Burney, in his "Tour in Germany," describes as a portable organ, used in processions, and formed entirely of reeds, was not something like our modern seraphine; for although he mentions the "Regal stop" in the organ at Haerlem as being an 8 foot reed pipe, yet I think this would be too long to be used in an organ for processions if it was of full compass. Mace, also, in his "Musick's Monument," names a 66 table-organ" of his contrivance. Might not this have been something of the same kind? May I be allowed to suggest that some of your scientific correspondents would confer a benefit upon musical mechanics if they would furnish a mathematically correct scale of the length, thickness at both extremities, and width of the tongues of the seraphine? At present, I believe no such scale is followed; for each maker adopts a different one. There are many considerations to be taken into the account in forming such a scale. If the tongues (especially of the lower notes) are too broad, they will, when in vibration, act as a tremblant upon the instrument; if they are too short, they must be filed very thin in order that they may articulate, consequently they will be lia ble to break; if they ave too long, the vibration will be continued after the fin ger is removed from the key, and wan unpleasant buzzing will be occasioned, unless dampers are used to check it; the strength of the tongues ought also to be proportioned to the weight of wind, or they will be continually destroyed, If a rule can be theoretically formed for the manufacture of these tongues, I imagine they will be regarded as pendulums (inverted) being fixed at one erd, and having the weight at the other, and having a certain number of vibrations to make in a given time for the production of a certain musical note. The requisite elasticity, length, and strength of spring, with the necessary weight of wind, I leave for mathematicians to determine. Perhaps the rule used by organ-builders in making the tongues of trumpet, &c, stops, would afford some guide, if any of your correspondents would furnish it. In conclusion, I have to say that if the scale I have adopted should be of any service, it will afford me pleasure to forward it for insertion in your valuable publication. Respectfully yours, N. S. HEINEKEN. Sir,-In your "Old Correspondent's" scientific solution of (). C. F.'s question, he has fully proved the impossibility of gaining 20 per cent, by the transaction; but it does not appear that he has assigned any manifest reason for it, as called for in the proposition. Perlaps the following simple explanation may make the subject better and more generally understood. The difference between d. and d., the buying and selling price of a single egg of the second parcel, is d., which is exactly 20 per cent, profit upon the d.; if, then, we take the wholed. in the form of per centage (20 per cent.) there remains no surplus profit, with any multiple of which to make up for the actual loss (12d.) occasioned by selling the |