The Austrian government offer a prize of one thousand ducats (nearly five hundred pounds) for the discovery of a system of working coal in fiery mines without shot-firing. The method must not be more expensive than that of ordinary blasting. It must not be capable of igniting fire-damp or coal-dust, and it must not leave any injurious products behind it. These are the chief conditions. An improved method of etching metallic surfaces has been invented by Mr A. Piper of Wolverhampton. The metal surface is first of all coated with gold, silver, nickle, brass, or any other metal desired, in the ordinary electro-plating bath. The design is then drawn upon it in some resinous or other acid-resisting medium, and the metal is immersed in an acid, which eats away the coating, and at the same time produces a dead or frosted appearance upon the exposed metal beneath. The resinous drawing is now removed by any suitable medium which will dissolve it, leaving the design in relief upon a frosted ground. If desired, the operation can be reversed by leaving a groundwork of plated metal, while the design is bitten out by the acid. A new stationary buffer-stop for railway stations and sidings was recently described in a paper read before the Institution of Mechanical Engineers by Mr A. Langley of Derby. This buffer-stop consists of two hydraulic cylinders fitted with pistons. The piston rods carry in front buffer-heads to meet those on the locomotive. There are also projecting rods behind the cylinders connected by chains with counterweights, to return the pistons after pressure to their former position. The pistons have a stroke of four feet; and it is calculated that this amount of depression would effectually stop a train without jerk or damage even if it were moving at the rate of eight miles an hour. Gases inclosed in iron cylinders under enormous pressure are now used in various branches of science and art, and are supplied commercially by many firms in various countries. The gases most commonly used are hydrogen and oxygen—for the lime-light—carbon dioxide, and nitrous oxide—this last being much employed as an anæsthetic by dentists. Hitherto, there has been much difficulty in controlling the outrush of gas from these cylinders, for the internal pressure often amounts to six hundred pounds on the square inch. By the aid of a new regulator, invented by Messrs Oakley and Beard of London, this difficulty is at once obviated. The regulator consists of a small india-rubber bellows inclosed in a brass box, which screws upon the nozzle of the gas cylinder. By an ingenious device, as the bellows top rises with the pressure of the gas, a screw valve descends upon the opening in the cylinder. In this way the user of the gas can regulate the outflow to his requirements. We understand that it is in contemplation to adapt the same principle to ordinary gas consumption in houses, so that the supply may always be adjusted to the number of burners in actual use.