high speed, a small diameter usually suffices. Plate XV. shows a large turbine-driven fan constructed by Messrs. C. A. Parsons and Co., and installed at the Clara Pit in Durham. It is 5 feet in diameter, and can deliver 120,000 cubic feet of air per minute at 2-inch water-gauge. A turbo-fan is installed at Hulton Colliery, Chequerbent, near Bolton, and is used to ventilate by suction two mines which are worked as one as regards ventilation. A short wooden drift leads the air from the top of the upcast shaft to a cabin in which the turbine is situated. A conical iron casting 5 feet long has its larger end of 7 feet 1 inch diameter connected to the drift, and its smaller end of 3 feet 7 inch diameter connected to a short cylinder of about 3 feet 7 inch diameter, in which works the fan. An iron bend, through which passes the fan-shaft, conducts away the air from the fan to the discharge cone. The turbine, besides driving the fan, also drives a 50-kilowatt dynamo which supplies current for lighting and for actuating the motor which drives the circulating pump for the condenser. The motor and pump are situated in a separate building from the turbine. The fanshaft is coupled to the low-pressure end of the turbine spindle, and the armature spindle to the high-pressure end of the same. The turbine, fan, and dynamo were constructed by Messrs. C. A. Parsons and Co. The pump for supplying the lubricating oil to the turbine, fan, and dynamo is driven from a shaft which is connected by a worm and worm-wheel to the turbine spindle, and rotates at 4 of the speed of the turbine. This shaft also, by means of an elliptical double-throw cam, actuates the relay valve for controlling the motion of the steam admission valve. The relay valve is conjointly controlled by a centrifugal governor. The exhaust pipe to the condenser is |