Application of the Congreve Rocket in the Whale Fisheries.The ship Fame has returned to Hull, and captain Scoresby has confirmed all that was stated in his letter of the 24th of June, inserted in some of the public papers in July last, respecting the important advantages to be derived from the use of the rocket in the whale fishery. The Fame has brought home nine fish, in the capture of the whole of which the rockets were successfully employed. After being struck by the rocket, the largest whale became an easy prey to its pursuers. In one case, instant death was produced by a single rocket, and in all cases the speed of the fish was much diminished, and its power of sinking limited to three or four fathoms. One of the largest finners, of 100 feet in length, a species of fish seldom attacked by the ordinary means, and of the capture of which there is scarcely an instance on record, in the northern seas, was immediately tamed by a discharge of rockets, so that the boats overtook and surrounded it with ease. Six out of the nine fish died in less than fifteen minutes; and five out of the number took out no line at all. One only survived nearly two hours, and one only took out more than a single line, by getting into a pack of ice, where the boats could not follow. The peculiar value and importance of the rocket in the fisheries is, that by means of it, all the destructive effects of a six, or even a twelve-pounder piece of artillery, both as to penetration, explosive force, and internal fire, calculated to accele rate the death of the animal, may be given with an apparatus not heavier than a musket, and without any shock or re-action on the boat; whereas it is obvious, that no boat applicable to the fishery of the whale can ever be made capable of sustaining the shock necessary to produce the same effects as the six or twelve-pound shell, by the ordinary means of artillery, or any thing in any degree approaching them. In fact, nothing larger than the harpoon gun could be applied; and the missile which could be discharged from such an implement, could neither have penetration, nor explosive force, sufficient to do any serious injury to the fish. With respect to the rocket, however, it is a fact that some of the smallest fired in the late experiment in the Fame, penetrated completely through the body of the fish, so that the effect of the explosion was visible on the opposite side-the fierce fire of the rocket fixed in the animal's inside, rapidly destroying life; and the effects, and report of the explosion, being distinctly perceivable within him, in one instance above stated, producing immediate death. Indeed, it is certain, that this might, in almost every case, be insured by increasing the power of the rocket, without increasing the inconvenience or incumbrance of the apparatus required to discharge it, and with as little re-action on the boat, as when the smallest rockets are used. In addition to this, it may be stated, that there is no doubt of the rocket ultimately dispensing with the operation of the hand harpoon, by conveying the line, and destroying the animal at the same time, and that without requiring the approach of the boat to the fish, within the limits of perfect security. It is also equally certain, that the large finners, never or rarely attacked in the north, may be rendered an easy prey by the application of the rockets. Improvement in Aerostation. It has been proposed, by a gentleman of Cork, to keep a balloon constantly in a favourable current of air, by decreasing or diminishing its specific gravity, so as to cause it to sink or rise at pleasure. For this purpose a copper vessel and a condensing pump, which will serve, in a great measure, as ballast, are attached to the from the latter. The machine consists of several wheels, two of which (one at either end) are furnished with 48 flails: these are put in motion by one man as he walks to and fro within the machine, and thus a single labourer is enabled to perform the work of a great number. The most complete success has attended the experiments that have been made, and there can be no doubt of the efficiency of the invention. 2. A Sawing Mill, which is also worked by a single person, without any assistance from water. 3. An Astronomical Watch, which indicates the difference of time in the principal places in different parts of the globe: this has been accepted as a present by the emWhen the balloon is rising M. Kuhaiewsky, in return, a magperor Alexander, who has sent too high, its volume is to be di-nificent snuff-box, and has asminished by condensing the hy signed him a sum to enable him drogen gas in the copper vessel. to continue his important laOn the contrary, when it sinks bours. too much, by turning a cock, the hydrogen is to be allowed to inMethod of saving Lives in Cases flate the balloon again. In case of Shipwreck or Fire.-Mr. John of a long voyage, it is recommended to have another similar Murray has found that the common musket may be employed in vessel, with a quantity of hy-propelling an arrow and line to drogen condensed in it, as a supply to replace any that might escape through the pores of the balloon. car. the shore from the ship, or vice versa. The arrow, made of hickery or ash, and loosely fitting the calibre of the musket, is discharged with gunpowder, the charge being less than the usual quantity. These arrows are three or four inches longer than the barrel of the musket, and are shod with iron at the point, having an eye, through which the line is threaded. The lower end enters a socket, which must be in complete contact with the wadding of the piece. The line never snaps, and the average distance to which the arrow and a logline can be projected may be estimated at 230 feet; in one case an iron rod was carried 333 feet. The arrow may also be projected over buildings on fire, and carry a rope ladder, which could be drawn over the roof by a line attached to the other side, and instantaneously afford a a fire escape. New Optical Machine.-Signor Amici, professor of Mathematics, at the university of Modena, has invented an instrument which he calls a catadioptrical microscope. It is contrived for the purpose of viewing objects of every description, diaphanous or opake, solid or fluid, without the necessity of dividing them into parts; and consists of a tube placed horizontally, as a telescope, and not vertically as the common microscope. At one extremity of this tube are several metallic mirrors, which reflect the object through a small hole be neath, corresponding perpendicularly to the glass which carries the object. The latter is moved up and down by a screw, under which a mirror is placed as in other microscopes; and it is easily and instantly magnified or diminished by changing the eyeglasses only. One great advantage attending this improved instrument is, that any object may be distinctly viewed, although immersed in a liquid half an inch beneath the surface; a circumstance which has hitherto been impracticable. A scale has also been contrived by which the objects are accurately measured. Picture-cleaning.-The French chemist, Thenard, has rendered an important service to the art of painting, having employed his oxygenated water, with great success in cleaning old pictures, where the white prepared from lead had become spotted with brown. It is not, perhaps, too much to expect, that the advancement of chemical knowledge will ultimately contribute much to this beautiful art, by furnishing it with more durable materials. Improved Barometer. — M. Barthe, of Strasburg, has constructed an instrument of this description, which announces every change of weather thirty hours previously to its taking place; and, what renders it still more valuable, it even prognosticates the approach of thunder-storms twelve hours before they occur. Crystallo-Ceramic.-A patent has recently been taken out for ornamental incrustations, called Crystallo-Ceramic, which bids fair to form an era in the art of glass-making. By the improved process, ornaments of any description, arms, cyphers, portraits, and landscapes, of any variety of colour, may be introduced into the glass, so as to become perfectly imperishable. The substance of which they are composed is less fusible than glass, incapable of generating air, and at the same time susceptible of contraction or expansion, as, in the course of manufacture, the glass becomes hot or cold. It may previously be formed into any device or figure by either moulding or modelling; and may be painted with metallic colours, which are fixed by exposure to a melting heat. The ornaments are introduced into the body of the glass while hot, by which means the air is effectually excluded, the composition being actually incorporated with the glass. In this way every description of ornamental glass-ware may be decorated with embossed white or coloured arms or crests. Specimens of these incrustations have been exhibited, not only in decanters and wine-glasses, but in lamps, girandoles, chimney ornaments, plates, and smellingbottles. It is the invention of Messrs. Pellatt and Green. Improved Carmine.-Liquid ammonia, digested with carmine at an atmospheric heat of 129 Reaumur, seizes its colouring matter, dissolves it, and leaves only a residuum of an earthy appearance and of a pale red. Se parate this colouring matter with ammonia, and it produces a most brilliant lustre, and succeeds perfectly with the help of concentrated acetic acid. The acid must be added by degrees to the alkaline tincture, until the ammonia is completely saturated. It forms a precipitate of extraordinary lustre; upon which the eye can scarcely rest. The extreme fine ness of this precipitate requires the addition of a little alcohol to the liquid, in order to diminish its density. This addition soon causes the colour to deposit, which then shows itself in all its brilliancy. The discoverer de canted the colourless liquid, and after washing the deposit with alcohol, he dried it in a small capsula. This beautiful colour may be of great use to miniature painters. Lacker for Brass-work.-To a pint of spirit of wine put one ounce of turmeric powder, two drachms of best annatto, and two drachms of saffron; let it stand ten days, shaking the bottle often, then filter it through coarse muslin into a clean bottle, adding three ounces of clean seed lac; and shake the bottle often for fourteen days. The brass, if large, must be first warmed, so as to heat the hand, and the varnish then applied with a brush. This varnish gives the brass rails of desks, &c. a beautiful appearance. Mr. Timbrell's Improvement in the Rudder and Steerage of Ships. - Experience has convinced every nautical man of the danger and inconvenience of attending the labour at the wheel, in consequence of the sea striking with violence into the vacuum between the stern-post and the rudder; this danger increases with the velocity of the ship, and during her rapid progress, the sea rushes with such weight and power into the chambers, and against the weather angle of the rudder, as to shake the whole stern-frame, and render the steering of the ship in boisterous wea> ther most laborious and dangerous. This improvement which traverses on the stern-post, acts as a minor helm, gives additional effect to the power of the rudder by the space of the vacuum it covers, and permits the water to pass smoothly from the ship's bottom along the sides of the rudder, without noise, agitation, or counteraction; thus reducing the manual labour at the wheel to the power of one man, and giving such ease and facility to the steering of the ship, as to render the short iron tiller perfectly secure in all weathers. The improvement consists of a flap, or minor rudder, traversing with the principal rudder, and attached to the stern-post; the flap covers the vacancy around the posts behind the rudder, or between the rudder and stern-post. This vacancy or space in a vessel of 1,200 tons burthen, is about 23 feet high, and 18 inches by 12 or 14 inches broad, and into this vacuity, when the helm is nearly aweather, the water rushes with such force in passing off from the ship's bottom, as to impede her progress and to make her steering difficult. In case of sternway, the flap, or minor-rudder, is turned back against the sternpost out of action. On the under part of the stern-post, a piece of copper is fixed to prevent ropes getting between it and the rudder; and it is recommended that the edges of the rudder be cut off, or rounded, down to light-water mark, to break the eddy, other wise occasioned by its passage through the water. Cleaning of Medals.-Professor Lancellotti, of the Royal Institute at Naples, read, at a late sitting of that society, an account of the process which he employs in order to remove from ancient silver medals the rust that covers, and often renders them illegible. He first lays the medal in oxydated acid of salts, afterwards in a solution of sal-ammoniac for a short time; then rubs it with a piece of linen until all the rust disappears. His experiments have always been attended with success; and the discovery is of importance to those who study numismatics, since a great number of silver medals, whose inscriptions have hitherto not been legible, may now be rendered so. On the Application of Mineral Colours to Stuffs, by M. Haussman.-Being myself a manufacturer of printed goods, and having some knowledge of chemistry, I succeeded, as long as forty-six years ago, in fixing the colour of Prussian-blue on cotton stuffs, and in changing olive colours, the mordant of which is alumine and oxide of iron, into very beautiful greens, by immersion into a colour-vat, slightly acidulated, and charged with Prussian-blue. These kind of goods, dyed in Prussian-blue, then into olive transformed into green, were at that time a considerable article of trade. By using processes similar to those which I employed for cottons, I obtained the same shades and colours on samples of silk; and for these last ten years, I have been able to fix Prussianblue on wool, and to produce with it on woollen cloth the same colours as on cotton and silk. I have even often had satisfactory results. The nitric solution of red oxide of mercury, precipitated on a sample of cotton cloth, has given me a very fine yellow : a like colour was produced by the precipitation, by ammonia, of a solution of gold; but this turned brown by keeping, probably by the loss of part of its oxygen. Suspecting that this salt of gold might prove fulminating, I dried the cloth with great precaution, but nothing of the kind occurred. The oxide of silver fixed on the cloth gradually became more and more dark, and therefore produced nothing beautiful. Cassius's purple precipitate of gold gave me curious results; for having been able to obtain it in a solution of a very fine purple tint, I obtained two samples on silk |