114 REPORT 1842. 



become entangled in several of these ; and the effect is not merely that a greater hold- 

 fast is obtained, but that the strain being oblique towards the centre, the stopper is 

 actually diminished in diameter by the force applied, and easily withdrawn, though its 

 resistance to pressure from within remains the same as to the felted stopper. It is a 

 peculiar property of the patent stopper, that India rubber will not slide on a smooth 

 dry surface, whilst it slides easily on a wet one ; therefore, in application, the stopper, 

 •which cannot be forced in dry, when wet slides with perfect ease into the mouth of 

 the bottle under the pressure of the thumb, and no more force than this is required in 

 stopping effectually bottled drinks. As rubber has the property of taking up about 

 one per cent, of water, the thin film of moisture between the surface of the stopper, 

 when wetted for application in the liquor to be bottled, and the mouth of the bottle, is 

 soon absorbed, the surfaces come into actual contact, and the stopper cannot be readily 

 drawn out, for its resistance to sliding is so great, that in a few hours the power of a 

 cork-screw is required to draw it : this quality to resist sliding renders unnecessary any 

 wiring or tying of the stoppers, even for effervescing liquors. The advantage there- 

 fore of the cotton core, as the stopper is now constructed, is, that whilst it holds with 

 equal firmness, it is more easily drawn by its diminishing under the force of the screw. 

 The roundness obtained by the new core thus made by machinery, now enables the 

 patentee to form the cylindrical sheet, on the surface of the rope itself, without a seam. 

 This again enables him to subject the stoppers to a heat of 150° without bursting ; and 

 this heat, whilst it perfectly purifies the stopper, by driving off the naphtha, gives the 

 patentee also the opportunity, of which he avails himself, of putting on the last end of 

 the stopper under this temperature ; thus the expanded air at this degree of heat is all 

 that the stopper contains when hermetically closed ; as it cools, the atmospheric press- 

 ure compels a closer contact of the covering, and no temperature in future purifica- 

 tion, or of climate, can affect them. 



Notice of Mr. Prosser's Method of making Earthenware or Porcelain from 

 dry Powder of Clay compressed. By Sir J. Robison, F.R.S.E. 

 The advantage was, that no warping or alteration of shape (excepting a little 

 shrinkage) took place in the burning. From the accuracy with which articles formed 

 by compression retained the shape of the mould, they could be fitted together very 

 easily and smoothly. Sir J. Robison showed a piece of tesselated pavement made 

 of these tiles, which, although laid together without cement, was perfectly smooth 

 on the surface. He wished particularly to introduce to their notice a roofing-tile 

 of a construction novel in this country : from the peculiar manner in which these 

 tiles united by imbrication, a little Roman cement rendered them perfectly water- 

 tight ; and from their not being absorbent, they were not liable to exfoliate, and 

 would, therefore, be almost imperishable. The old form of tile weighs about 

 105 lbs. per square yard, while this only weighs 58 lbs. They were manufactured 

 at Stoke-upon-Trent, by Minten and Co. 



M. Bergeron, through Prof. Vignoles, explained his method of instantaneously 

 casting loose the locomotive engine from the carriages. It is effected by a con- 

 trivance attached to the brake, and worked when necessary by the brakesman. The 

 engine was attached by a large chain, the last link of which was held, not by a hook, 

 but by a bar which could be shot back or forward like a common door-bolt or lock ; 

 by drawing this back out of its staple, it was of course drawn out of the chain, 

 which being cast loose, all connexion between engines and carriages was sundered. 



Mr. Taylor exhibited some specimens of a new kind of drawing-paper, in which 

 the novelty lay in the cement, by which the paper was mounted on a species of linen 

 or canvas. The advantages offered were, equality of texture, neatness in junctures, 

 and uniformity in expansion and contraction in both directions. 



Mr. L. Schwabe explained his method of spinning glass, and brought forward 

 specimens of the glass thread, and also of the cloth woven ; he showed the spinning 

 machine with which this was effected, and also displayed many other filamentous 

 substances from which he had succeeded in fabricating cloths — Assam silk, fibres of 



the Pinna, &c. 



On Wigstons Self-Acting Railway Signals. By James Thomson, C. E. 



