Krauss. Wilkinson. Rowan. Diameter of cylinder.........d 5.5 in. 6.5 in. 5.1 in. Length of stroke.............l 11.8 in. 9 in. 9.8 in. Diameter of wheels...........D 31.5 in. 27.5 in. 29.5 in. Pressure at which boiler is worked...........P 220 lb. 147 lb. 191 lb. (p(d^{2})l)/(2D).............E 1,210 lb. 1,509 lb. 805 lb. Total heating surface........S 105 sq. ft. 105 sq. ft. 64 sq. ft. Grate surface................G 2.7 sq. ft. 5.4 sq. ft. 3.1 sq. ft. Surface of condenser.........C 274.482 s. ft. None. 861.120 s. ft. Weight in running order (motor only)...............P' 15,400 lb. 15,400 lb. 9,020 lb. Weight in running order (total)....................P" - - 15,400 lb. Contents of water tank.......- 28.24 cub. ft. 13 cub. ft. 4.2 cub. ft. Contents of coal bunks.......- 14.12 cub. ft. 12.5 cub. ft. 8.5 cub. ft. P'/E 12.7 lb. 10.2 lb. 11.2 lb. P"/E - - 19.125 lb. P'/S 146 147 140 P'/G 5,722 2,855 2,889 C/S 2.6 - 13.4 C/G 102 - 275 The air, after being forced through the first pump cylinder, passed successively through the other three, the diameters of which were of proportionately decreasing sizes, viz., 8.2 in., 5 in., 3.5 in., and 2 in., and the air on leaving each cylinder passed on its way to the next cylinder through a coiled pipe immersed in flowing water to remove the heat generated. This cooling surface amounted to nearly 54 sq. ft. The cooling of the air was very efficient. In an experiment made on this question, the temperature of the compressor did not vary to the extent of 9° F. in charging the reservoir from 40 to 63 atmospheres, occupying an hour and a half, the consumption of water during the time being about 1,400 gallons. The fixed reservoirs were of about 240 cubic feet capacity. The motor formed part of a compound vehicle, which may be said to have consisted of two parts joined together by an articulated corridor, the whole being covered by a roof which was approached from the platform behind by an easy staircase. On this roof were seats for outside passengers. The front part of the compound vehicle contained the motor, as well as a compartment for six inside passengers, with roof space for twenty passengers, and weighed about 15,400 lb. when empty; the hind part contained accommodation inside for twelve passengers, and outside for fourteen passengers, and weighed 6,600 lb.