The valves are conical, double-seated, and of cast iron, and the inlet and outlet valves are placed the one above the other, the seats being also conically ground and inserted through the cover of the valve chest. Both inlet and outlet valves are actuated from above, and are removable upward, an arrangement which admits of the valves being more easily examined than when the two are actuated from different sides of the valve chest. To carry out this idea the inlet valves are furnished with two guides, which, passing upward through the stuffing-box, are attached to a hard steel cross piece, which receives the action of a bent catch turning on a pin attached to the levers, t1, t2, t3, t4. The exhaust valves, on the contrary, have only one guide each, which passes upward through the seat of the admission valve, through the valve itself by means of a collar, and through the stuffing-box. It is furnished with hard steel armatures, through which the levers, z1 z2, Fig. 3, act upon the exhaust valves. [Illustration: BORSIG'S IMPROVED COPOUND BEAM ENGINE. FIG. 4] The governor effects the acceleration or retardation of the loosening of the catch actuating the steam valve by means of hard steel projections on the shaft, v1, the position of which, by means of levers, is regulated by the governor, which in its highest position does not allow the lifting of the inlet valve at all. The regulation of the expansion by the governor from 0 to 0.45 takes place generally only in the case of the high-pressure cylinder, while the low-pressure cylinder has a fixed rate of expansion. Only when the low-pressure cylinder is required to work with steam direct from the boiler is the governor applied to regulate the expansion in it. An exact action in the valve guides and a regular descent is secured by furnishing them with small dash pot pistons working in cylinders. Into them the air is readily admitted by a small India-rubber valve, but the passage out again is controlled at pleasure.--_The Engineer_. * * * * * TO DETECT ALKALIES IN NITRATE OF SILVER--Stolba recommends the salt to be dissolved in the smallest quantity of water, and to add to the filtered solution hydrofluosilicic acid, drop by drop. Should a turbidity appear an alkaline salt is present. But should the liquid remain limpid, an equal volume of alcohol is to be added, which will cause a precipitate in case the slightest trace of an alkali be present. * * * * * POWER HAMMERS WITH MOVABLE FULCRUM. [Footnote: Paper read before the Institution of Mechanical Engineers.--_Engineering_.] By DANIEL LONGWORTH, of London.