is driven off suddenly; the properties of lime burnt at a slow heat will differ much from the properties of the preceding Theme chanical mixing is also of the greatest importance; the Barrow lime is a natural hydraulic lime, but it must be well beaten with water and silica or sand.

Mr. Blunt, from America, gave, at the request of the Chairmans an account of the system of signals which were employed in the geometrical operations now carrying on in America.

February 7, 1837.

The PRESIDENT in the Chair.

The conversation on artificial cements being resumed, several members expressed their opinions on the causes to which the hardening of mortar was to be referred. Hydrate of lime is the basis of all mortars, but this will not make a water mortar, or cement, without the addition of a metallic oxide. The addition of clay will effect this, but most clays contain a metallic oxide.

ル

Mr. Francis Bramah gave the analysis of Dutch Terras, of Basalts, and of Puzzolana, according to different experimenters ; in all these there is a considerable proportion of iron; and the addition of any of these to hydrate of lime will make a water mortar. Thus it appears that we must carefully distinguish between a good mortar, and a good water mortar or cement. Hydrate of lime is the basis of both. Good mortar depends for its excellence on the slow absorption of carbonic acid, and the slow absorption of this is, according to Tennant, the essential condition for good mortar. It is remarkable that, according to Pliny and Vitruvius, the Romans kept their mortar for three years, and it is now the custom among builders to bury mortar, or to keep it in a cellar; it is thus prevented from absorbing carbonic acid from the atmosphere, or, in other words, from being reconverted into limestone. According to some experiments of Tennant it appears, that mortar in 34 years will regain 63 per cent. of the carbonic acid of which it had been deprived. The absorption of carbonic acid being the condition of mortar hardening, if it be

used under circumstances such that this absorption cannot take place, as lunder water, some other material must be supplied, and the addition of a metallic oxide appears to supply the required element.1361

With respect to an hypothesis of Kirwan's which had been mentioned, as to the peculiar properties of iron and clay, Mr. J. I Hawkins stated a singular fact which had come under his own observation, namely, that the rust of iron has a peculiar disposi tion to travel through moist clay; the rate of this transfer was in one case about one inch per month.

"On Locomotive Engines, and the means of supplying them. By Jacob Perkins, M. Inst. C. E."

The object of this paper is to show how locomotives may be supplied. The practical defects of the present system of locomotives arising from the furring up or bruising out of the tubes of the boilers, Mr. Perkins proposes that steam should be generated through the medium of surcharged steam. He states, that if a tube hermetically sealed be filled to th of its contents with water, the steam arising from the water will not acquire sufficient elastic force to burst the tube, but will have a remarkable property of transferring heat. The steam being saturated with heat, requires no more, and the tube being vertical, this surcharged steam becomes a floating agent, through which the heat ascends its own levity, so that the top of the tube would become red hot, were it not immersed in water. The difference between pure and surcharged steam is, that surcharged steam gives up its heat without condensing it, whereas pure steam must necessarily condense as it parts with its heat. Mr. Perkins states, that a boiler has generated steam on this principle under the action of a fervent heat during the last seven months, and without the least leakage or incrustation.

Mr. Perkins then details the advantages which may be gained from the adoption of his principles, and proceeds to make some remarks on the manufacture of locomotives. He recommends the

division of labour, that the engines should all be fac-similes, and engine laces best adapted for their pro

each part be manufactured at the

duction. The paper concludes with observations on the mos. effective application of steam; on the best velocity of the piston, and relative proportions for the diameter and length of the cylinder.

Mr. Blunt, at the request of the President, then stated some facts respecting the American steamers. The double boats had been given up, and the average speed of the best boats was fifteen miles per hour. One boat, whose length is 220 feet, and breadth eighteen feet, has an average speed more than the preceding. They had recently introduced a ferry boat, which might, he conceived, be extremely serviceable in our rivers; in the Thames for instance, where there are a great number of vessels. The boat had bows at each end, so that it could go either way, and rudders at each end worked by one helm; the boat is thus steered at both ends. The rudders are placed in a semicircular chamber at each tend, and can be reversed round; they are worked by a chain passing round the wheel of both and crossing in the middle, so that the boat is brought about in the same direction by the contrary action of the two bows. The wheel and chain cannot get out of order, and the rudder begins below the water, so that the boat can go through the broken ice.

*

Such a ferry boat will go round without going her length, which is about 100 feet.

Mr. Blunt had repeatedly gone a distance which he knew, from actual trigonometrical measurement, to be seventy-four miles in five hours. The boats completed the distance from New York to Albany, not less than one hundred and fifty miles in ten hours. The speed of these boats, as compared with that of the boats in this country, is not to be wondered at, when it is remembered that the boats are built simply and expressly for speed. The Americans pay great attention to the form of their boats; the water is smooth, the engines are placed on the deck and the boilers on the wings; and they spare no expenditure of power provided speed can be obtained.

and alot of

bas zalimiz-ost ed is blyore among at 30ft model to motivib List of Patents

bist de autostume od tr8q dose

Granted by the French Government from the 1st of July to the 31st of

To Laplace, Brothers, and Lemeille, of Valenciennes, for a new bmethod of manufacturing.

Gonlofret and Co., of Marseille, for the manufacturing of a new dibmineral manure.

Ferdinand Meisner, of Paris, for an improved paper machine. Dubreuil, of Juval, near Gisors, for a means of superseding the -use of weights and ropes for regulating the progress of the workbarbeam in calico frames.

Marie Joseph Denis Fariot, of Paris, for a new steam-engine. Sylvain Boudart, of Paris, glover, for a machine called by him doschirometer, for measuring the hand.

Philippe Mathieu and Co., of Vaugirard, for a new means of oe obtaining and using certain resinous products,

Guinard, Brothers, of Marseille, for a means of cutting glass zo and crystal.

--

Honoré Celestin Piovoux, of Lyon, for an improved apparatus applicable to the manufacturing of silk fabrics. Bourbon de Rouvre, of Chaumont, for an apparatus for washing and pressing instantaneously the pulp of beet root. M Xavier Jourdain, of Altkirck, for a new mechanism for driving the shuttle, applicable to all weaving frames. etpod szá

Jean Baptiste Justin Lassie, for improvements in windmills. f Maness, Mallet, and Co., of Valenciennes, for cast iron conical vases used for crystallising sugar.

2. Jean André Guenard, of Courtenay, for a sawing machine, odt tro François Burg Jernior, of Paris, for the application of a prea pared sponge to the dressing of issues. posla 918 esaipao eft sd ADDITIONAL SPECIFICATIONS INROLLED BY THE FOLLOWING .banisido

PATENTEES.

To John Brooks, of Manchester, represented by Mr. Perpigna,

#esmoToT advocate of the French and Foreign Office for Patents, Rue de ༩༠༥༩ Choiseul, on his patent for the preparing of certain colours used in the printing of calico.

To Eude and Cailly, of Offranville, represented by Mr. Perpigna, on their patent for the means of imitating on a small vessel all the motions of the sea.

- Auguste Jean Baptiste Gallais, of Paris, represented by Mr. Perpigna, on his patent for a preparation of milk called lactoline.

Thomas Elliot and Co., of Pont Andemer, represented by Mr. Perpigna, on their patent for producing malleable iron.

Patents granted by the French Government from the 1st of January to the 1st of July, 1837.

PATENTS FOR FIFTEEN YEARS.

To Edward Ashworth, of Lancaster, represented in Paris by Mr. Perpigna, advocate of the French and Foreign Office for Patents, Rue de Choiseul, for improvements in machines used for spinning cotton, silk, and other fibrous substances.

- Frederic Edward Harvey, of Tipton, county of Stafford, represented by Mr. Perpigna, for improvements in the manufacturing of metallic tubes and rails, applicable to various purposes. Ambrose Brewin, of St. Quentin, represented by Mr. Perpigna, for a method or methods of weaving or manufacturing divers kinds of goods and wares, and for machines or machinery applicable thereto.

John Stephens, of London, represented by Mr. Perpigna, for improvements in the construction of steam generators. ›› -Michel Emmanuel Valadon, architect, represented by Mr. Per

pigna, for improvements in the construction of bottles used for by admitting and delivering, by the same orifice, solid or liquid sub

stances.