Modern Gasworks Practice

THE MECHANICAL HANDLING OF MATERIALS 297 usually driven by electricity, mounted on a steel framework. Two frameworks are provided (an inner one and an outer), the inner frame rising or falling inside the larger one so that any tier of retorts may be charged. A hinged apron plate is lowered into the front of the retort mouthpiece, and acts as a connecting trough. between the retort and the machine, the bottom of the apron plate forming the bottom of the chain. The front length of the chain. (called the “ fire-length ”) is- very strongly constructed, and acts as a pusher head during the outward stroke. The operations of charging and discharging are performed simultaneously, about 30 seconds being necessary to empty and refill a 20-foot retort. The external diménsions of the machine are about 8 feet 6 inches long by 13 feet high. The standard pattern of the original type of Fiddes-Aldridge machine is fully illus-trated in Fig. 214-, from which part of the framework has been removed so as to give a clearer view of the driving wheel and chain.