The accompanying engravings illustrate Edwards' patent gas engine, made by Messrs. Cobham & Co., Stevenage, Herts, recently exhibited at York. In our engravings, _a_ is the foundation plate of the engine, having the bearing, _b_, in which the crank shaft, _c_, revolves; _d_, an inclined plate upon the foundation, _a_, to which the cylinder, _e_, and casing, _f_, are bolted; _g_ is a piston working in the cylinder, _e_, and having a hollow rod or trunk, _h_, to which is jointed the connecting rod, _i_, which drives the crank pin, _k_. The guide, _l_, fits upon the hollow trunk, _h_, and is itself surrounded by the air casing, _m_, which communicates with the casing, _f_, through openings, _n n_, in the inclined plate, _d_. The guide, _l_, has openings, _o o_, through which air enters the casing, _m_, when the hollow trunk, _h_, is at the inner end of its stroke; _p_ is the exhaust pipe, and _r_ is a casing round the cylinder, _e_, through which water may be made to circulate by pipes at _s, t_. The valve seat, _v_, fits into the cylinder, _e_, and has holes, _w_, for the admission of air, and _x_ for the admission of gas through the central pipe, _y_. The valve, _z_, consists of a disk of metal covering these holes and guided by a spindle, A, the outer end of which is fitted with a metal or India-rubber spring at B, and a regulating nut, C. The gas pipe, _y_, is shown supplied from a flexible bag, D, the supply to which from any convenient source is regulated by a cock or valve at E. The piston, _g_, contains a disk exhaust valve, G, the spindle, H, of which is fitted with a closing spring, I, and the end of the spindle is pressed down during the inner stroke of the piston by a tail-piece, K, on the inner end of the connecting rod, _i_. Holes, L, open from the hollow piston above the exhaust valve, G, into the cylinder round the hollow trunk, _h_, and thence to the exhaust pipe, _p_. At or near one-third of the stroke of the piston a firing valve, P, is arranged, having an inlet hanging valve of the usual kind, through which a flame burning outside is drawn when the valve is uncovered by the piston, _g_. The outer end of the casing, _f_, is closed by a cover, R, to which the valve seat, _v_, and gas inlet pipe, _g_, are connected.