towards perfection as the expansive use of steam itself was found to be when first discovered. The action of this new expansion gear is founded upon a correct theory of calculation, beautifully carried out into a practical shape. The gear is connected with the governor, so that the engine itself regulates the operation of the steam, according to the work to be performed. The invention has been secured by patents in Great Britain, and also in the principal continental states. Amongst other testimonials which we have seen of the saving effected by its adoption, are the following. The first is from Mr. Crosskill, of the Beverly Iron Works, who writes to Mr. Chapman, that the "practical results of your patent expansion gear, more than realizes my expectation, for I feel certun that my engine is doing more than onethird more work, with one-third less quantity of fuel. The apparatus only wants to be known to be generally adopted, more espe cih by those parties who are in want of power, which was the case with me, for I could only do a part of my work, but with the use of your invention I can do the whole.'

Messrs. Grimston and Co., of the Clifford Mills, Wetherby state, that with the "Expansion gear attached to their engine, on a fair trial of three clear days, the saving of fuel was about 8 cwt. per day, which they consider very well for an eight horse engine.' Messrs. Bainbridge and Son, of the Tees Paper Mill write as follows:

We have had Mr. Chapman's patent expansion gear in operation some months. to our steam engi. e of 30 horse power, and have submitted it to various tests, and the results have been, in the greatest degree, such as to prove it an appendage of inestimable worth to a steam-engine.

"We have satisfactorily shown to ourselves and engine-man, that there is a full saving of 25 per cent. in fuel, to produce the same quantity of manufactured goods; and we have further proved that the engine will carry full 25 per cent., or one-fourth more machinery to a better purp, with the patent gear, than it will with our governors only regulating the engine.

And we have further satisfied ourselves by diagrams taken with the steam indicator (under our own inspection, and afterwards calculating the same), that the engine works more effectually and powerfully with the patent expansion gear, all these experiments nearly show the same results, and prove the great benefit derived from the application of the invention."

We hope shortly to be able to present our readers with a full description of this most important improvement upon the steamengine.

413

ACTION OF SEA WATER ON IRON. [From the Proceedings of the Inst. C.E.] The analysis of a piece of iron converted, by the action of sea water, into a substance resembling plumbago, was read by Mr. D. Mushet.-In this communication Mr. Mushet gives the result of his analysis of a piece of the iron heel-post of a vessel, called the John Bull, which, by the effect of salt water, was converted into a substance resembling plumbago. This substance was of a dark brown colour, and easily cut by a knife; on being exposed to a red heat, in a crucible, it lost about 20 per cent. in weight, and on being exposed to a white heat for four hours, it lost about 60 per cent., and came out a light mass of very brilliant carburet. This shining carburet was then used as a carbonaceous substance for the reduction of an oxide of iron, but was less efficacious than the same quantity of the charcoal of wood. From these and other experiments, Mr. Mushet considers 100 parts to be composed as follows:

Carbonic Acid and Moisture.. 20
Protoxyde of Iron

Silt, or earthy matter.
Carbon

35.7

7.2

41.1

ON THE EXPANSION OF ARCHES. BY G.

RENNIE, ESQ.

The expansion of solids, which has excited the attention of mathematicians since the investigations of La Hire, in 1688, on a rod of iron, is of particular importance in the construction of bridges, the security of which may be affected by the dilatation and contraction consequent on changes of temperature. Periodical motions, referable only to changes of temperature, were observed by Vicat, in a stone bridge, built over the Dordogne, at Souillac, and have frequently been noticed in structures of all kinds. The different expansibilities of stone and iron have been considered an objection to the use of cast iron pillars in connection with stone, to support the fronts of buildings; but the experiments of Mr. Adie, of Edinburgh, led him to the conclusion that no danger is to be apprehended from a change of temperature affecting cast iron and sandstone in any great degree, as their expansion, so far as regards buildings, may be considered the same. Arguments from this source were employed against the arches of Southwark-bridge, and the experiments set forth in this communication were undertaken with a view of ascertaining the effect of temperature on these arches. Three sets of experiments were made, the first in January, 1818, when the main ribs and diagonal braces rested on their centres, and before any of the spandrils and road plates had been

put upon them; the second in August and September of the same year. The rise was measured by the insertion of small wedges, by which the rise was ascertained to about

th of an inch. The most extensive set of experiments were made on the eastern arch. Great care was taken in observing the thermometers, of which there were three, one in the open air, another among the ribs, and the third inserted in the iron of the rib. The result of nine experiments gave as a mean, a rise of of an inch for 1° Fah. The effects of changes of temperature were also observed in the stone bridge over the Thames, at Staines. After the arches had obtained their full settlement, openings were observed in the joints of the parapets immemediately over the springing of the arches, and a distortion, or sinking, of the upper curve of the parapets. A wedge was inserted into some of these openings, and the lowest point of its descent, in the month of January, marked, The same wedges were carefully inserted every week until May,

when they would no longer enter, and the joints became firmly closed. At this period, however, the joints immediately over the crowns of the arches, which had, during the winter, been quite close, were open. From these facts it followed, as a necessary consequence, that in winter the arch contracting descends, and the spandril joints opened, and in summer the arch expanding rose, and closed these joints, and opened those at the crowns. Thus the joints of the parapets, which were made of single slabs of granite for the whole height, became good indicators of the change of temperature. It had also been observed in the Waterloo and other bridges, that, joints made good in the winter with Roman cement, were found crushed in summer. The details of these experiments, and of others, on the expan sion of a large portion of the frieze plates, and the calculations to which they give rise, occupy the principal portion of this communication.

Subject of Design.

Time for which the protection is granted.

Registered Proprietor's Name.

Register.

Moses Poole, of Lincoln's-inn, gentleman, for improvements in pumps for raising and forcing water and other fluids. (A communication.) Jan. 30; six months to specify.

William Brockedon, of Queen-square, Middlesex, esq., for improvements in the means of retaining fluids in bottles, decanters, and other vessels. Jan. 31; six menths.

Philippe Marie Moindron, of Bedford-place, Russell-square, merchant, for improvements in the construction of furnaces and in boilers. (A communication.) Jan. 31; six months.

William Cubitt, of Gray's-inn-road, builder, for an improvement or improvements in roofing. Jan. 31; six months.

Croft on William Moat,f Thistle-grove, Bromp

ton, esq., for a new and improved method of ap. plying steam power to carriages on ordinary roads. Feb. 5; six months.

Wilkinson Steele and Patrick Sanderson Steele, manufacturing ironmongers, of George-street, Edinburgh, for improvements in kitchen ranges for culinary purposes, and apparatus for raising the temperature of water for baths and other uses. Feb. 5; six months.

William Isaac Cookson, of Newcastle-uponTyne, esq., for certain improved processes or operations for obtaining copper and other metals from metallic ores. Feb. 5; six months.

Thomas Myerscough, of Little Bolton, manager, and William Sykes, of Manchester, machine maker, for certain improvements in the construction of looms for weaving or producing a new or improved manufacture of fabrics, and also in the arrange. ment of machinery to produce other descriptions of woven goods or fabrics. Feb. 5; six months.

Samuel Carson, of Caroline-street, Coleshill, Eaton-square, Middlesex, gentleman, for improvements in apparatus for withdrawing air or vapours. Feb. 5; six months.

Joseph Needham Taylor, of Plymouth, captain in the Royal Navy, for improvements in steamboats and vessels making applicable the power of the steam engine to new and useful purposes of navigation. Feb. 8; six months.

John Werthemier, of West-street, Finsburycircus, printer, for certain improvements in preserving animal and vegetable substances and liquids. (A communication.) Feb. 8; six months. Robert Beart, of Godmanchester, miller, for improvements in apparatus for filtering fluids. Feb. 8; six months.

Amand Deplanque, of Leicester-square, gentleman, for improvements in looms for weaving. (A communication.) Feb. 8; six months.

Edmund Rudge, jun., of Tewkesbury, tanner, for a new method or methods of obtaining power for locomotive and other purposes and of applying the same. Feb. 8; six months.

James Hancock, of Gloucester-place, Walworth, for a method of forming a fabric or fabrics applicable to various uses, by combining caoutchouc or certain compounds thereof with wood, whalebone, or other fibrous materials, vegetable or animal, manufactured or prepared for that purpose, or with metallic substances manufactured or pre pared. Feb. 8; six months.

George Eugene Magnus, of Manchester, merchant, for certain improvements in manufacturing, polishing and finishing slate, and in the application of the same to domestic and other useful purposes. Feb. 8; six months.

Robert Willis, of the University of Cambridge, clerk, for improvements in apparatus for weighing. Feb. 12; six months.

David Napier, of York-road, Lambeth, engineer, for improvements in the manufacture of projectiles. Feb. 12; six months.

Antoine Blanc, of Paris, merchant, and Theophile Gervais Bazille, of Rouen, merchant, for certain improvements in the manufacturing or producing soda, and other articles obtained by or from the decomposition of common salt or chloride of sodium. Feb. 12; six months.

Thomas Robinson Williams, of Cheapside, gentleman, for certain improvements in the manufacture of woollen and other fabric or fabrics of which wool or fur form a principal component part, and in the machinery employed for effecting that object. Feb. 14; six months.

Joseph Clarke, of Boston, printer, for improve ments in piano fortes. Feb. 14; six months.

Gerard Ralston, of Tokenhouse-yard, merchant, for improvements in rolling puddle balls or other masses of iron. (A communication.) Feb. 22; six months.

Richard Cuerton, jun., of Percy-street, Middlesex, brass founder, for improvements in the manu. facture of cornishes, mouldings, and window sashes. (A communication.) Feb. 22; six months.

415

William Cook, of King-street, Regent-street, coachmaker, for improvements in carriages. Feb. 22; six months.

Thomas Kerr, of Forecrofts Dunse, in the county of Berwick, esq., for a new and improved mortar or cement for building, also for mouldings, cast. ings, statuary, tiles, pottery, imitations of soft and hard rocks, and other useful purposes, and which mortar or cement is applicable as a manure for promoting vegetation and destroying noxious insects. Feb. 22; six months.

John Hanson, of Huddersfield, engineer, for certain improvements in meters for measuring volumes of gas, water and other fluids, when passed through them, and, in the construction of cocks or valves applicable to such purposes. Feb. 22; six months.

William Winsor, of Rathbone-place, artists' colourman, for a certain method or certain methods of preserving and using colours. Feb. 22; six months.

Job Cutler, of Lady Pool-lane, Birmingham, gent., and Thomas Gregory Hancock, of Highgate, Birmingham. aforesaid, mechanist, for an improved method of cutting corks and constructing the necks of bottles. Feb. 22; six months.

William Brindley, of Northwood-street, Bir. mingham, for improvements in apparatus employed in pressing cotton wool and goods of various descriptions. Feb. 25; six months.

Thomas Huckrale, of Over Norton, Oxford, farmer, for improvements in ploughs. Feb. 25; six months.

Thomas Farmer, of Gunnersbury House, near Acton, Middlesex, Esq., for improvements in treating pyrites to obtain sulphur, sulphureous acid, and other products, Feb. 25; six months.

John Wilson, of Liverpool, lecturer on chemistry, for an improvement or improvements in the process or processes of manufacturing the carbonate of soda. Feb. 25; six months.

Richard Kingdon, of Gothic House, Stockwell, surgeon, for certain improvements in apparatus for the support of the human body, and the correction of curvatures and other distortions of the spine of the human body. Feb. 25; six months.

Thomas Milner, of Liverpool, safety-box manufacturer, for certain improvements in boxes, safes, or other depositories, for the protection of papers, or other materials, from fire. Feb. 26: six months. William Morritt Williams, of Bedford-place, Commercial-road, professor of mathematics, for an improved lock and key. Feb. 27; six months.

Rowland Macdonald Stephenson, of Upper Thames-street, in the city of London, civil engi neer, for certain improvements in shifting and working stage scenes, and other theatrical machinery. Feb. 28; six months.

LIST OF SCOTCH PATENTS GRANTED BETWEEN THE 22nd OF JANUARY AND 22nd OF FEBRUARY, 1840.

Robert Lorimer, brass founder, No. 45, Jamaicastreet, Glasgow, North Britain, an improvement or improvements on stoves. Sealed Jan. 25, 1840; four months to specify.

Miles Berry, of Chancery lane, Middlesex, (communication from a foreigner), an invention or discovery by which certain textile or fibrous plants are rendered applicable to making paper, and spinning into yarns, and weaving into cloth, in place of flax, hemp, cotton, and other fibrous materials commonly used for such purposes. Jan. 27.

John Jones, of Westfield-place, Sheffield, York, a new frying and grilling pan for the cooking of steaks, chops, and other meats. Jan. 29.

Robert Hervey, of Manchester, Lancaster, drysalter, certain improvements in the mode of preparing and purifying alum, alumina, aluminous

mordants, and other aluminous combinations and solutions, and the application of such improvements to the purposes of manufacture. Jan. 31.

Francis Worrell Stevens, of Chigwell, Essex, school master, certain improvements in apparatus for propelling boats and other vessels on water. Feb. 1.

William Isaac Cookson, of Newcastle-upon-Tyne, esquire, certain improved processes or operations for obtaining copper and other metals from metallic ores. Feb. 3.

George Wilson, of St. Martin's-court, St. Martin's-lane, Middlesex, stationer, an improved paper cutting machine. Feb. 3.

Miles Berry, of Chancery-lane, Middlesex (communication from a foreigner), certain improvements in machinery or apparatus for making or manufacturing pins, and sticking them in paper. Feb. 5.

Godfrey Anthony Ermen, of Manchester, Lancaster, cotton spinner, certain improvements in machinery or apparatus for spinning, doubling, or twisting cotton, flax, wool, or other fibrous materials, part of which improvements are applicable to machinery in general. Feb. 5.

James Capple Miller, of Manchester, Lancaster, gentleman, certain improvements in printing calicoes, muslins, and other fabrics. Feb. 7.

John Alexander Philip de Val Marino, of No. 17, Clifford-street, Bond-street, Middlesex, esquire, certain improvements in the manufacture of gas, and in the apparatus employed for consuming gas for the purposes of producing light. Feb. 7.

John Francis Victor Fabien, of King-street, Lon. don, gentleman, (communication from a foreigner), improvements in pumps. Feb. 12.

Jonathan Fell, of Workington, Cumberland, ship builder, improvements in building ships and other vessels. Feb. 12.

John Reynolds, of Victoria Hotel, Euston-square, Middlesex, Esq., improvements in the manufacture of salt. Feb. 12.

Henry Pinkus, late of Pennsylvania, in the United States of America, but now of 79, Oxford-street, Middlesex, gentleman, improvements in inland transit, some of which improvements are applicable to, and may be combined with, an improved method of, or apparatus for, communicating and transmitting, or extending, motive power, by means whereof carriages or waggons may be propelled on railways or roads, and vessels may be propelled on canals. Feb. 19.

plane surface, the interstices are filled with fine sand, and then boiling pitch is poured over all. This pitch, from the porous nature of the wood, is speedily absorbed; and on a quantity of sand being strewed above it, the operation is complete, and a pavement constructed which is found to be extremely durable, and which seems to me to suffer much less injury from the frost than the stone causeway. The honour of the invention is due to Mr. Gourief, and I have no doubt he will ultimately see it adopted in most of the great towns towards the north. It is the custom of the peasantry to cut down the trees at some distance from the root, and thus a great deal of wood will be turned to a useful purpose, which would otherwise only encumber the ground. Every peasant, besides, by means of his axe alone, is able to construct such a pavement; and in Russia, hands are both plenty and cheap.

Use of Varnish of Dextrine or Starch in the Fine Arts-In the sitting of the Academy of Sciences, Monday, 26th August, Baron De Silvestre made the following remarks on the occasion of M. Arago's communication on the preservation of photographic images. He observed that it would be interesting to try dextrine for this purpose, as he himself, for more than two years, ad successfully used this substance jor varnishing pictures newly painted in oil, water colour drawing, coloured lithographs, and for the permanent fixation of pencil drawings. He had also obtained from dextrine a glue, which he found superseded with advantage all other gluey substances, and particularly mouth glue. In these different applications dextrine is mixed with water in different proportions; two parts to six of water for varnish, and in equal parts for glue. He observed that he always added one part of alcohol in the composition of the varnish, and half a part in that of the glue. The mixture should be always filtered before being used for varnishing pictures and fixing drawings, and in this latter case, a fine wet muslin should be spread over the drawing, before covering it with the mixture of filtered dextrine. The description of these processes, and of the results obtained, is given in the Bulletin de la Societe d'Encouragement pour l'Industrie Nationale, for the 2d of August, 1837.

Compression of Gas.-In a memoir on the com. pression of gases, and on the reduction of variable pressures, into regular pressure, M. Seguin gives the Academy of Sciences a description of a new pump, with a regulating apparatus, for the compression of gas for illumination obtained from the distillation of animal substances. The pump is so arranged as to give the maximum force at the mo ment of the course when the gas presents the maximum of resistance by the diminution of its volume; to work in a vertical position without loss of gas, and without the piston being immersed in fluid; and lastly to avoid, by means of a particular mode of transmitting power, the use of guides, which would cause a friction in the piston rod.

Saw Setting Instrument.-A correspondent who signs himself " ." states that for more than two years he has seen an instrument precisely the same as that figured and described in our 862d number, and communicated by Mr. Morehen, builder, of Cambridge, as of his invention, exposed for sale at the different fairs of Norfolk and Suffolk, by itinerant vendors of tools. The instrument is not in general use amongst carpenters, and if Mr. Morehen be not truly the inventor, he might have contented himself with the merit of being the means of its publication, and not have appropriated that of its invention. If he was the author of the invention previous to the date abovementioned, and others appropriated it to his disadvantage, we shall be happy if he will enable us to set the matter right with our readers.