=Hauling.=--A working platform, made up of 5-ft. sections, was built inside the tunnel and kept close to the shield. On this platform two lines of industrial railway tracks with switches and sidings at the locks, and a heading, were laid for hauling materials and spoils. These lines converged into a single track in passing through the air locks. At the shaft elevators, they terminated in a steel plate floor to avoid switches. Between the locks of the bulkheads was installed an electrically driven cable system, to haul the loaded muck up grade and to empty the flat cars. From the first bulkhead to the shaft, the cars were hauled up grade by a steam hauling engine. At the Manhattan end there was one 10-H.P. engine for each tunnel, while at Weehawken one 25-H.P. engine served for both tunnels. Each shaft contained two elevators driven by a double-cable, reversible single-drum steam-hoisting engine. A grouty frame was built over the shafts, and on the platforms over this frame were narrow-gauge tracks, extending from the elevators to the muck-chutes and to points where the lining segments were loaded on the cars. The elevators were arranged to stop at both the ground and the grouty platform levels. The rolling-stock at each of the tunnels consisted of 75 flat cars for moving the tunnel segments, and of about 50 muck cars, each of 1¹⁄₄ cu. yd. capacity. =Plant.=--The plants located at each end of the tunnel near the shafts were almost identical. Each consisted of three 500-H.P. Stirtling boilers, which supplied steam at 150 lbs. pressure. Feed water was supplied by three 13¹⁄₂ metropolitan injectors, and two Blake duplex pumps. Two Worthington surface condensers, each of 2250 sq. ft. condensing surface, took care of the exhaust from the engines and compressors. Condensing water was pumped from the river through a 16-in. pipe. The high-pressure air was supplied by a duplex Ingersoll-Sergeant compressor, with cross-compound steam end 14 × 26 × 30 ins. and simple water-jacket air cylinders 13¹⁄₄ × 36 ins. Its capacity at 100 r.p.m. was 1085 cu. ft. free air per minute. The maximum pressure was 130 lbs. per sq. in. The air for the pneumatic working was supplied by three 14 × 26 × 30 in. duplex Ingersoll-Sergeant compressors. The maximum capacity of the three was 12,000 cu. ft. free air per minute at 125 r.p.m. and a discharge pressure of 50 lbs. per sq. in. The suction air was taken from the outside about 10 ft. above the roof of the engine house. Three aftercoolers, 32¹⁄₂ ins. × 11 ft. 4 ins., each having 809 sq. ft. cooling surface of tinned brass tubes, cooled the low-pressure discharge to within 10° F. of the temperature of the cooling-water. From the aftercoolers, the air passed into three steel receivers each 54 × 12 ft., placed outside the engine room and fitted with weighing safety valves. The receivers were connected to two 10-in. mains; one serving the north, the other the south tunnel. A fourth receiver of the same