of differences, whether they are positive or negative, or of both kinds; and that with perfect confidence he would venture to construct an engine that should compute numbers depending on ten or twelve successive orders of differences. It is a remarkable property of the machine, that the greater the number of differences, the more it will outstrip the most rapid calculator. This machine, by the application of certain parts, may be employed in extracting the roots of equations, and the degree of approximation will depend on its magnitude. Mr. Babbage has sketches of two other machines, one by which the product of any number by any other number may be found; and another by which all prime numbers from 0 to 10 millions may be determined. He has also a fourth machine, whose plans are in a more advanced state, by which tables having no order of differences constant may be constructed. This last is immediately applicable to the construction of Logarithmic and Astronomical tables of every kind; and in order to avoid the errors which might be produced in copying and printing the numbers in the common way, the ingenious inventor states, that he has contrived means by which the machines shall take, from several boxes containing type, the numbers which they calculate, and place them side by side; thus becoming at once a substitute for the computer and the compositor. In order to demonstrate the practicability of executing these views, Mr. Babbage has actually constructed a machine which will produce any tables where second differences are constant, and has exhibited it to some friends, who have witnessed its performance. In the computation of a series of numbers from the formula 12 +a+41, they were at first produced rather slower than they could be taken down by a person that undertook to write the numbers as they appeared, but as soon as four figures were required, the machine was at least equal in speed to the writer. Method of preserving Iron and Steel from rust.-Greasy and oily, or resinous substances have hitherto formed the basis of the different preparations proposed and employed for this purpose; but in the former, when rancidity comes on, an acid is produced, which corrodes the iron; and the latter, when dry, are apt to crack, and thus afford an inlet to moisture. But melted caoutchouc, or India rubber, Mr. Aikin has found to possess peculiar advantages in prepreserving the surface of iron from being acted upon by the atmosphere, arising from its little susceptibility of chemical change when exposed to the air; from its treacly consistence, under all ordinary temperature; from its strong adhesion to the surface of iron or steel; and, at the same time, from the facility with which it is removed by a soft brush charged with warm oil of turpentine. The finger or a soft brush are the most convenient implements for applying the caoutchouc ; and, as soon as the article has been covered, it ought to be set up on end, in order that the excess may drain, which will take place in a day or two. The temperature for melting caoutchouc is nearly equal to that required for the fusion of lead. An Artificial Triton. At Scheveningen, a Mr. Andrew Scheerboom made the experiment of riding on his horse, which he had provided with his newly-invented apparatus, into the breakers of the sea, which rose to the height of 12 feet; and having advanced 400 yards directly into the water, he returned to the shore, waving his handkerchief, amidst the acclamations of thousands of spec tators. Damp in Walls.-An easy and efficacious way of preventing the effect of damp walls upon paper in rooms has lately been used with considerable success. It consists of lining the wall or the damp part of it with sheet lead, purposely rolled very thin; this is fastened up with small copper nails, which not being subject to rust are very durable, and the whole may be immediately covered with paper. The lead is not thicker than that which is used in the chests in which tea is imported, and is made in sheets, of which the width is about that of common paper hangings. Monochromatic Lamp Proceedings of the Royal Society of Edinburgh. April 15.-A paper, by Dr. Brewster, was read, intituled, "Description of a Monochromatic Lamp, with observations on the Composition of different Flames, as modified by Reflection, Refraction and Combustion." The chief object of this paper was to describe the principles and construction of a Monochromatic lamp, for illuminating objects with a homogeneous flame, which the author succeeded in constructing, after many unsuccessful attempts. By illuminating microscopic objects with this lamp, a distinctness and perfection of vision was obtained, which extends widely the power of the microscope, and enables it to detect de licate structures, and minute organizations, which are beyond the reach of observation when common light is employed. The author pointed out the application of this lamp to various purposes, both practical and scientific, and particularly to the measurement of minute optical phenomena, such as those of refractive powers, double refraction, and polarisation, and the phenomena of periodical colours. As the yellow light discharged from this lamp has an invariable character, the measures of these and other phenomena, taken in such a light by different philosophers, may now be referred to as an unchangeable standard, and they will also have the advantage of being made in the most luminous rays of the spectrum, and of being referable to rays that have nearly a mean refrangibility. The author likewise pointed out the manner in which the prismatic spectrum is attacked, and finally extinguished, by the action of dif ferently-coloured absorbing media; and he has established, in opposition to the deductions of Dr. Wollaston and Dr. Young, that the yellow light has a separate and independent existence in the solar spectrum. Purification of Oil. A discovery has been made in Denmark for purifying common fish oil, and rendering it equal to the best sperm, by means of animal charcoal, which is made, in a peculiar manner, from beef bones which have been boiled. The charcoal is mixed with the oil, and repeatedly agitated for two months, after which it is filtered with twelve strata of similar charcoal, used as soon as made. The quantity of gas evolved by the bones in the operation is considerable, and is used for lighting the manufactory and adjacent buildings. The residuum is mixed with clay for fuel; the loss in the process by the residuum is estimated at 15 per cent, and the gain is equal to 40 per cent, leaving a balance in favour of the discovery of 25 per cent. Electrical Conductors for Ships. -Seventy years have elapsed since Dr. Franklin demonstrated the efficacy of metallic conductors in protecting buildings from the destructive effects of lightning. Although the application of conductors on land is generally judicious, and their advantages are admitted, yet, on shipboard, where the effects of lightning are most to be dreaded, from the inflammability of the materials of which the ship and stores are usually composed, the introduction of electrical conductors has been lament ably neglected or injudiciously em ployed. This, indeed, may in some measure be traced to the difficulty of placing any fixed or contiguous conductor in a situation so liable to change and motion as the mast and rigging of a ship; and consequently the only species of conductor that has been adopted is a chain, or long links of wire, one end of which is designed to be hoisted to the mast-head, whilst the other passes over the side of the ship, and communicates with the water; but, independently of its defective construction, from its small dimensions, the inconvenience of being constantly hoisted, and its consequent liability to be injured, are very obvious. This species of conductor is therefore usually kept packed in a case, and only hoisted on the approach of danger, which it may then be too late fully to avert. To remedy these inconveniences, Mr. Harris the masts a slip of copper, which proposes to place in the back of is to be continued to the interior consequently, coming into contact or hole of the cap of each mast ; with the mast above, the continuity will be preserved without The conductors of the lower masts the upper masts being lowered. are to be continued to the keel, and made to communicate with one or more copper bolts in conthe water. It must be clear, theretact with the exterior copper or fore, that this arrangement preserves a permanent conductor, so long as any part of the mast is continued, and as the masts of a ship may be considered as mere points, when contrasted with a thunder cloud, thus armed they are virtually pointed conductors. To those acquainted with the action of points on charged electrics, it will be obvious, and not too much to presume, that such masts will be highly efficacious in silently depriving a thunder cloud of its charge, thereby giving to considerable importance. ships a degree of security of very Harris was induced to submit a From these considerations Mr. model of a complete mast, furnished with permanent conductors, to the inspection of the honourable navy board, who expressed their decided approbation of the principle, and requested him to exemplify its efficiency by an experiment, which was carried into effect on board the Caledonia, at Plymouth, in the presence of the missioner Shield, several captains navy board, sir A. Cochrane, comin the navy, and the principal officers of the Dock-yard, in the following manner: cutter having had a temporary The Louisa mast and topmast fitted with a copper conductor, according to Mr. Harris's plan, was moored astern of the Caledonia, and at the distance of eighty feet from the cutter a boat was stationed with a small brass howitzer. On the tiller head of the Caledonia were placed the electrical machine and an electrical jar, with the outer coating of which a line was connected, having a metallic wire woven in it: this line being carried out of the starboard window of the wardroom, terminated in an insulated pointed wire in the immediate vicinity of the touch-hole of the howitzer; a similar line was passed from the larboard window, which communicated with the mast head of the cutter; and at the termination of the bolt through the keel, a chain was attached, connected with another insulated pointed wire in the boat, placed in the vicinity of the touch-hole-the space between the insulated points being the only interval in a circuit of about 300 feet, from the positive to the negative side of the jar. Some gunpowder being placed in contact with the conductor in the cutter, and the priming in the interval of the insulated points, the jar was charged, and the line attached to the mast-head of the cutter being brought into contact with the positive or inside of the jar, a discharge of electric matter followed, which was passed by the line to the mast-head, and by the conductor through the powder to the chain in the water by which it was conveyed to the interrupted communication in the boat where it passed in the form of a spark, and discharging the howitzer, returned to the negative or outside of the jar by the line leading into the starboard window, thereby demonstrating that a quantity of electric matter had been passed through the powder (without igniting it) in contact with the mast of the cutter, sufficient to discharge the howitzer. Mr. Harris then detached the communication between the keel of the cutter and the positive wire in the boat, leaving that wire to communicate with the water only, but this interruption did not impede or divert the charge, as the discharge of the howitzer was effected with equal success as in the first instance, the water forming the only conductor from the cutter to the boat. In order to demonstrate that a trifling fracture or interruption in the conductor would not be important, it was cut through with a saw, but this produced no material injury to its conducting power. These trials, carried on under the disadvantages of unfavourable weather, convinced all present of the efficacy of the plan, and called forth the decided approbation of the navy board. Sir T. B. Martin requested Mr. Harris to superintend the equipment of the masts of the Minden of 74 guns, and of the Java frigate, preparatory to its general introduction into the navy. PATENTS. GEORGE LINTON, of Gloucesterstreet, Queen-square, Middlesex, mechanist; for a method of impelling machinery without the aid of steam, water, wind, air, or fire.-Dec. 22nd, 1821. Richard Ormrod, of Manchester, iron-founder; for an improvement in the mode of heating liquids in boilers, and thereby accelerating and increasing the production of steam; communicated to him by a person residing abroad.-Jan. 7th, 1822. Richard Summers Harford, of Ebbro Vale iron-works, Aberistwyth, iron-master; for an improvement in that department of iron commonly called puddling.-Jan. 9th. James Harris, of St. Mildred'scourt, London, tea-dealer; for an improvement in shoes for horses and cattle.-Jan. 9th. William Ravenscroft, of Serle-street, Lincoln's-inn, peruke-maker; for a forensic wig, the curls whereof are constructed on a principle to supersede the necessity of frizzing, &c. and for forming the curls in a way not to be uncurled; and also for the tails of the wig not to require tying in dressing; and, further, the impossibility of any person untying them.-Jan. 14th. D. Loescham, of Newman-street, and J. Allwright, of Little Newportstreet; for an improved keyed musical-instrument, comprising in itself many qualities never hitherto produced in one instrument. Communi. cated to him by a foreigner.-Jan.14th. A. Gordon, of London, and D. Gordon, of Edinburgh; for improvements and additions in the construction of lamps, and of compositions and materials to be burned in the lamps. -Jan. 14th. D. Gordon, Edinburgh, esq.; for improvements and additions to steampackets, and other vessels; part of which improvements are applicable to other naval and marine purposes. Jan. 14th. A. Applegarth, Duke-street, Lambeth; for improvements in printing machines.-Jan. 14th. J. Winter, of Acton; for improvements on chimney-caps, and in the application thereof. Sealed at Edinburgh, Jan. 23rd, 1821. J. Heard, of Birmingham court; for improvements on working apparatus. Edinb. Jan. 23rd, 1821. J. Hague, Great Pearl-street, Spitalfields; for a method of making metallic pipes, tubes, or cylinders, by the application and arrangement in the apparatus of certain machinery and mechanical powers.-Jan. 29th. Sir W. Congreve, bart.; for improved methods of multiplying facsimile impressions to any extent.Jan. 29th. P. Ewart, Manchester; for a new method of making coffer-dams.-Jan. 29th. R. Bill, Newman-street, for an improved method of manufacturing metallic tubes, cylinders, cones, or of other forms, adapted to the construction of masts, yards, booms, bowsprits, casks, &c.—Feb. 5th. F. L. Talton, New Bond-street; for an astronomical instrument or watch, by which the time of the day, the progress of the celestial bodies, as well as carriages, horses, or other animals, may be correctly ascertained. Partly communicated to him by a foreigner. -Feb. 9th. G. H. Palmer, Royal Mint; for improvements in the production of heat, whereby a considerable saving of fuel is obtained, and the total consumption of smoke may be effected.-Feb. 12th. J. F. Smith, esq. Dunston-hall, Chesterfield; for improvements in dressing of piece goods made from silk or worsted, or of both these materials. -Feb. 12th. S. Davis, Upper East Smithfield; for an improvement upon the lock for guns, &c. enabling the lock to be used upon the percussion principle, or with gunpowder, without charging the lock or hammer.-Feb. 12. T. Brunton, of the Commercialroad, chain-cable and anchor manufacturer; for improvements upon the anchor.-Feb. 12th. E. Peck, of Liverpool; for ma chinery to be worked by water, applicable to the moving of mills, and other machinery of various descriptions, or |