for supplying their Simplex engine, which we have already described. Altogether about 3000 horse-power have been supplied by them on this system, and have given repeated proof of the value of this process of generating poor gas, especially in France, where poor French coal, which can be used, is cheaper than imported English anthracite. _Gardie gas-producing plant._—This apparatus is characterized by the use of high-pressure air at about 80 lbs. per square inch, mixed with steam at the same pressure; this arrangement being more concentrated only requires small plant. The generator is of peculiar construction, without any grate, the coke being held up on shelves. The air and steam enter the generator by a ring of twyers, and a small window is pierced at the side through which the attendant can see if the proper degree of incandescence is maintained. The fuel is poured in through a hopper in a similar manner to other generators already described. The gas is produced at a high temperature, and is made to heat a coil through which the steam passes, which is thus economically superheated. After accomplishing this duty the gases pass on to a scrubber, formed by two concentric tubes of different heights, and travel on straight to the gasometer. The air is compressed in a reservoir by a special pump, and is heated by the waste gases from the cylinder of the motor. These various heating arrangements, therefore, prevent as much as possible any loss of waste heat. Some of the operations described are novel and interesting, and the gas produced is very rich, having a heat of combustion of over 1400 calories, and very little ammonia is produced. The result of this is that only rudimentary scrubbers are required, other systems requiring elaborate methods of cleansing the gases. The only drawback to the apparatus is the reservoir of compressed air, which necessitates a pump using up power.