521. Furneaux, J. B., and Butler, E. Jan. 7. Gas and explosive-vapour engines.-The engine comprises two explosion cylinders 1, 1<a> and one expansion cylinder 6 ; a four-stroke cycle is performed in the explosion cylinders, and the products from each alternately pass into the expansion cylinder, where they expand to below atmospheric pressure and draw a flushing-charge through the explosion cylinders. The crank of the cylinder 6 is about 190‹ in advance of those of the cylinders 1, 1<a>. Valves and valve gear; igniting.-All the distributing-valves are balanced in one piece and carried on a rotating shaft, driven by worm or chain and bevel gear from the crank shaft at a quarter its speed. They are of the kind described in Specifications No. 6990, A.D. 1890, and No. 24,881, A.D. 1896. The charge is supplied from an inspirator 15 described in these Specifications and in No. 15,598, A.D. 1887, and, after passing a throttle valve 15<a> controlled by a governor adjusted by a hand-wheel 18 and spring, is admitted through the ports 19, 20, 21, 22, or 22<a> to one of the cylinders 1, 1<a>. The exhaust passes through ports 24<a>, 24<b>, and 25 to the cylinder 6, and after expansion escapes into the atmosphere through ports 27 and the pipe 28. The air for flushing the cylinders is controlled by ports 29<a>, and passes by lateral pipes 31 containing non-return valves to the cylinders 1, 1<a>. The valve is slightly tapered, and because it expands during working it is secured between a spring 35 and a gland 34 which the valve tends to screw up as it rotates and so to slacken the valve ; the gland is provided with a turning-lever, and its motion is limited by a setscrew and stops. The valve may also control admission to two platinum igniting-tubes leading to clearance spaces in the brackets that secure them. Commutators 39, 39<a> for electric igniters 23, 23<a> may he carried on the valve shaft. Starting.-The apparatus is of the kind described in Specification No. 4604, A.D. 1895. A reservoir is charged with an explosive mixture by hand and ignited therein, the gases being admitted to one or both of the explosion cylinders through pipes 45 and valves 44 which open behind the pistons after they have performed about a quarter of their outstrokes. The reservoir may be charged with products from the cylinders for re-starting through these valves and pipes, the valves being arranged as both stop and non-return valves. The reservoir is in continuous communication with the explosion cylinder during starting, the gases being admitted in due course to the expansion cylinder. The admission of the starting-charges may be effected by the main valve. Steam may be used instead of burnt gases.