52 ANNUAL OF SCIENTIFIC DISCOVERY. 



that fifteen workmen, with the use of this machinery, can make 150 

 casks a day ; whereas the same number of persons, using only manual 

 labor, could scarcely produce a seventh part of that number. The im- 

 portance of the invention, and the application of steam-power to it, 

 may be imagined from the fact that the great brewing firms of the 

 metropolis afone expend many thousand pounds annually in cooperage, 

 and the expenditure of the navy is still greater, and that the demand 

 of the vintages of the Continent is so great that a great deal of wine is 

 lost from the difficulty of furnishing vessels to hold it. 



NEW ROOFING. 



A PATENT has been recently granted, in England, to Mr. Cowper, for 

 improvements in coverings for buildings, by means of tiles, or plates of 

 sheet-iron rendered applicable for that purpose by coating it with an 

 enamel or composition capable of enduring and protecting the metal 

 from the weather. Tiles, according to this manufacture, may be of any 

 suitable form, with a view to render them more or less ornamental, 

 combined with utility. The body of the tile, which is of thin sheet- 

 iron, is cut or stamped of the proper shape. It also has a raised head 

 formed round the edge, to prevent the water running off the tile, with 

 the exception of the lower end, where it drips on to the next. Two 

 holes are also punched for fixing the tiles to the wood-work. The upper 

 or narrow end of the tile is bent at right angles, which is introduced 

 in an opening between supporting laths or strips of wood. The hook, 

 or right-angled portion, sustains the tile, while two nails, introduced at 

 the holes, steady and keep it in its place. In lieu of the nails before 

 referred to, to fix the tiles, the patentee sometimes rivets a hook so as 

 to project on the under side of the tile ; the stein of the hook is riveted 

 through a hole in the metal plate before it is enamelled, which, when 

 so coated, is impervious to water, and obviates the necessity of an India 

 rubber washer under the head of the nail, which is required when fas- 

 tened by nails through the holes. The coating of these tiles is applied 

 in two separate compounds, the one as the body, and the other as a 

 glaze for the surface of the composition. The coating for the body con- 

 sists of sand or silica. The glaze, or second coating, is applied in the 

 shape of a fine powder, which is dusted on the wet coating until the 

 entire surface is covered. The powder, adhering to the moist coating, 

 causes it to set in some measure, when the tile is deposited in a drying- 

 room, previous to baking or firing. The tiles may be rendered orna- 

 mental by the application of coloring matters, according to any design 

 or pattern, which are burnt in, and thereby rendered indelible, as well 

 understood in porcelain manufactures. London Mining Journal. 



ON TILE APPLICATION OF CHILLED CAST-IRON TO THE PIVOTS OF ASTRO- 

 NOMICAL INSTRUMENTS. 



THE following paper was read before the British Association, by Mr. 

 May : 



" It has long been known that if a mould for casting iron in be 



