villages are of one piece with the back-scene; and while nature presents objects to us through a cone of visual rays drawn from the eye, the stage represents them in an exactly inverted position - that is, we see them through the base, instead of through the vertex of the cone. By M. Foucault's ingenious and artistical plan, all these inconveniences are obviated. The sky being so often required, he has made the upper part of it fixed, of a dome-like shape, as in nature; the lower or perpendicular part is of canvas stretched on frames, and arranged cylindrically, so as to form a panorama, the end of which cannot be perceived from any point of the house. His mountains or towns of the background are independent of the sky, and stand forth in real relief; so do his trees or shrubs, which are made to rise from or descend below the floor. As for those objects which are nearer the foreground, they are made of two pieces, the lower one to sink down, the upper one, a fly, to be drawn upward when a change of scene is required. His views of the sea or of interminable plains display a vast expanse never yet seen on a stage; rich architecture is also cut out, and shows beautifully on the fixed sky of the background, which, however, is so contrived that all the phenomena of storms, sunset, approaching night, travelling clouds, with varying illuminations, etc., are imitated with surprising fidelity. SQUARING THE CIRCLE. M. Robinet has presented to the French Academy a series of equations laboriously worked out and represented as having a remarkable approximation to accuracy. The proportion of various multiples and fractions of the diameter to the circumference is given, and it is stated that "the side of a square equivalent to a circle of a diameter equal to unity = 140.000,0006 = 0.8862269." A NEW SLOPE-LEVEL, BY M. RIBOT. This instrument is designed to solve practically either of the following inverse problems, namely, to find the slope per metre of a given line; or, to set a line to a given slope per metre (or per yard). The instrument is so simple as scarcely to need description. The horizontal distance between the feet or points of support is exactly one metre (or yard). The right hand foot of the figure is capable of protrusion by a screw, and is provided with a scale to measure the amount of this protrusion. When the two feet are on a level, the index is at the zero of the scale. If you want to determine a given slope, project the foot until the instrument stands on the slope; the protrusion measured on the scale gives the slope in terms of the distance apart of the feet (metres or yards). If you want to establish a given slope, set the foot to the indicated point of the scale, and adjust your plane to the instrument. The lower bar of the instrument may be graduated so that the plummet shall read angles of slope. — Bull. Soc. d' Encour. pour l'Indus. Nationale. A NEW MODE OF CONSTRUCTING CASKS. A new method of constructing casks has been recently patented by John Connolly, of Boston. It consists in making the heads of the cask of iron, or other metal, so arranged that the iron head serves at once·· one. as a head, a cap for oozing staves, and as a head-hoop, all combined in The head may be screwed on, the flanch or hoop part of the head having a female screw cut on it which cuts a worm for itself, and embeds in the stave as it goes on; or it may be barbed with concentric rings, and driven on with a hammer. This latter method, the patentee considers as generally preferable. The advantages of this improvement for preventing leakage and furthering the durability of the casks are considered to be very great. Mr. Connolly also recommends the construction of casks of iron in the place of wood, with heads applied in accordance with his improvement. The body of the cask might be rolled out in one piece, or it might be of two, three, or more pieces, which, being ground at joints, or rebated, or tongued and grooved and put together in any way with packing, would insure a tight joint, if well bound, as at present, with hoops. A cask so constructed, of boiler-iron, could be more readily "shooked" and "set up" than a wooden one. If dented, it could be beaten out. No more shrinkage, with its consequent leakage and labor, would then occur. Such casks would last for generations. A NEW BRICK AND MORTAR ELEVATOR. There is no operation in all the arts in which the waste of labor is more palpable than that of carrying up brick and mortar in erecting buildings. In order to raise forty or fifty pounds, the hod-carrier is required to exert muscular effort to raise his own weight (some one hundred and fifty pounds) in addition, thus involving a waste of about three-fourths of the power expended. An invention to economize the power required in this operation, devised by Mr. T. F. Christman, of Wilson, North Carolina, is substantially as follows: An endless chain, formed of iron links, passes around two pulleys, one at the ground, and the other at the top of the wall. The pulleys have spurs which take into holes in the belt, to prevent slipping, and the upper pulley is furnished with a crank for turning it. Hoppers are secured upon the upper side of the belt for receiving the brick, and as the wall rises, the belt is lengthened by the insertion of additional links, which are furnished with hooks so that this may be readily done. — Scientific American. NEW MATERIAL APPLIED TO THE ARTS. At the great London Exhibition, 1862, a new material applied to the manufacture of fancy articles, such as picture-frames, canes, inlaidwork, &c., attracted considerable attention. It is obtained from several species of marine plants, washed up on the shores in the vicinity of the Cape of Good Hope, South Africa, but principally from the laminaria buccinalis. It is of a dark color, and when fresh, it is thick and fleshy, but when it is dried it becomes compact and its surface looks like a beautifully-grained deer's horn. After it becomes dry and hard it can be rendered soft again by steeping in water, and in this condition it may be stretched and formed into various shapes. When dry it can also be reduced to powder, then made plastic by soaking in water, and in this condition it may be struck into almost any shape in a die press. It comes out of the moulds like articles formed of gutta percha. The discoverer of the use of this substance prepares the plant by cleaning it first with weak caustic alkali, and then with dilute sulphuric acid, after which it is washed, and before it is quite dry it may be pressed into sheets or any other form. It then may be rendered very hard by steeping it in a hot solution of alum, after which it is removed to a hot room where it is dried, and retains its shape afterward. Reduced to powder it may also be mixed with various substances, like india rubber, and moulded into a great variety of articles. When it is bleached, by treating it first with a warm alkaline solution, and afterward with sulphurous acid gas, it resembles ivory and may be used as a substitute for that material. MANUFACTURE OF STRINGS FOR MUSICAL INSTRUMENTS, The London Mechanics' Magazine publishes the following interesting article on the above subject: A manufacture, of which comparatively little is known, is the preparation of the substance usually termed catgut, though for the most part made from the dried, twisted, peritoneal coverings of the intes tines of sheep. Catgut cord is used for a variety of purposes where strength and tension are required, as for the strings of musical instruments, for suspending clock-weights, bow-strings for hatters' use, and for archers' bows. The manufacture of musical strings requires a great amount of care and skill, both in the choice of materials and in the manufacturing processes, in order to obtain strings combining the two qualities of resistance to a given tension and sonority. Until the beginning of the last century, Italy had the entire monopoly of this trade, and they were imported under the names of harplings, catlings, lute-strings, &c.; but the trade is now carried out, with more or less success, in every part of Europe. However, in the opinion of musicians, Naples still maintains the reputation of making the best small violin strings, because the Italian sheep, from their leanness, afford the most suitable material; it being a well ascertained fact, that the membranes of lean animals are much tougher than those of high condition. The smallest violin strings are formed by the union of three guts of a lamb (not over one year old), spun together. The chief difficulty in this manufacture is in finding guts having the qualities before mentioned, namely, to resist tension, and giving also good vibrating sounds. It is far more easy to arrive at the proper point in the making of harp, double-bass, and other musical strings, and the manufacturer is not so much circumscribed in the choice of the proper material. The tension upon the smallest string of the violin, which is made of only three guts, is nearly double that on the second string, formed by the reunion of six guts of the same size. In the preparation, the sheep's guts, well washed and scoured, are steeped in a weak solution of carbonate of potash, and then scraped by means of a reed cut into the shape of a knife. This operation is repeated twice a day, and during three or four days, the guts being every time put into a fresh solution of carbonate of potash, prepared to the proper strength. In order to have good musical strings, it is indispensable to avoid putrid fermentation; and as soon as the guts rise to the surface of the water, and bubbles of gas begin to be evolved from them, they are immediately spun. In spinning, the guts are chosen according to their size; combined with three or more, according to the volume of the string required, they are fastened upon a frame, and then alternately put in connexion with the spinning-wheel, and submitted to the required torsion. This operation performed, the strings, left upon the frame, are exposed for some hours to the vapor of sulphur, rubbed with a horse-hair glove, submitted to a new torsion, sulphured again, further rubbed, and dried. The dried strings, rolled upon a cylinder and tied, are rubbed with fine olive oil, to which one per cent. of laurel oil has been previously added. The oil of laurel is supposed to keep the olive oil from becoming rancid. The gut-strings employed by turners, grinders, and for cleaning cotton, &c., are made with the intestines of oxen, horses, and other animals. These, cleared by putrefaction of the mucous and peritoneal membranes, and treated by a solution of carbonate of potash, are cut into straps by means of a peculiar knife, and spun in the same way as the musical strings. The uses of bladders and gut for holding lard, for covering gallipots and jars with preserves, as cases for sausages, polonies, &c., and other domestic purposes, are well known. Lately, however, the vegetable parchment, as it is termed (which is ordinary paper steeped in sulphuric acid), has come into extensive use for this purpose. Insufflated, or inflated guts, are chiefly employed for the preservation of alimentary food. They have to pass through a long series of modifications and processes, before becoming fit for use. The end of these preparations is, to free the muscular membrane of the intestine from the two other membranes covering it, the peritoneal and the mucous. The first operation of scouring consists in freeing, by means of a knife, the gut from the grease attached to it, and also of the greatest part of the peritoneal membrane. The scoured guts are washed and turned inside out, then tied together, put into a vat without any more water than that adhering to them, and left in this state to undergo a putrid fermentation. The time required for this operation will be from five to eight days in winter, and two or three days only in summer. If the fermentation were pushed too far, the guts would be disorganized: to avoid this inconvenience, the workmen are often obliged to add some vinegar, in order to neutralize the ammoniacal compounds formed, and also because fermentation is slow in the presence of acids. After this fermentation, the mucous membrane is completely decomposed, and the remaining portions of the peritoneal membrane are easily taken off. The guts are then well washed, and insufflated (inflated). This operation is performed in the same way as swelling a bladder, with this difference, that the extremity of the gut is tied by a ligature, serving also to join a new gut insufflated (inflated) in the same way. During this operation, the guts exhale the most noxious smell, and workmen employed at such work could not blow or insufflate many days in succession without having their health affected. In order to prevent that inconvenient, unhealthy process of manufacture, the Société d'Encouragement of Paris proposed a premium for a chemical process enabling the manufacturers of these articles to dispense with putrid fermentation. The process suggested by Mons. Labarraque, the successful candidate, is remarkable for its cheapness and the facility of its application. In following the method recommended by this chemist, these animal matters can be worked more easily, and kept for a longer time without evolving any noxious smell. After The guts, previously scoured, are put into a vat containing, for every forty guts, four gallons of water, to which 14 pounds oxychloride of sodium, marking 13° on the areometer of Beaumé, is added. twelve hours of maceration, the mucous membrane is easily detached, and the guts are free from any bad smell; by this method, the process of insufflation is more easily performed. The insufflated guts are suspended in a dry room until the desiccation is complete; and, once dried, the extremities by which they were tied together are cut, and, in pressing the hand over the length of the insufflated (inflated) gut, the air inside is completely taken out. The guts are then submitted to fumigation by sulphur, in order to bleach and to preserve them from the attacks of insects. After this last operation, the guts are fit for use. Besides a large home supply of bladders, England imports several hundred thousand a year, packed in salt and pickle, from America and the Continent; and the aggregate value of the bladders used in Great Britain, is stated at £40,000 or £50,000. NEW METHOD OF PREPARING GUNPOWDER. Mr. W. Bennett, of England, has invented a new method of manufacturing gunpowder, the ingredients consisting of lime, nitre, sulphur, and charcoal; the lime is dissolved in a sufficient quantity of water to bring the other elements into a paste. The lime, after having been made into a solution, is strained through a fine sieve; this solution is then added to the other ingredients, and the whole is put into a mill, and ground until it becomes a paste; it is then taken out of the mill, and passed between two rollers, one grooved and the other plain. The paste, by passing between the rollers, is formed into long strips of a triangular shape; it is then carried on an endless web or canvas over some hot tubes, which are heated by steam, hot water, or any other artificial heat which may be applied; by this means, the strips are easily broken into grains. This mode of manufacture prevents a great deal of danger, as the powder is pulverized and brought into grain while in a wet state. The lime makes a firm grain, resists the damp, and gives it a degree of lightness which increases the bulk 25 per cent. over ordinary gunpowder, —a great advantage for blasting purposes. Plaster of Paris, Roman or Portland cement, or other strong cementing substance, may be used as a substitute for lime. And the patentee finds that for blasting purposes the following proportions answer well, -that is to say, nitre, 65 lbs.; charcoal, 18 lbs.; sulphur, 10 lbs.; and lime, 7 lbs.; but the proportions may be varied according to the strength required. |