In the three classes of engines of Division II. certain differences occur between hard and soft coal burners. The print on page 68 illustrates the plan of the soft coal or wood burner. In the hard coal burner the fire-box is made longer and shallower; the rear drivers are brought farther forward, and the three pairs of drivers are arranged so that the distance between centres of rear and main drivers is the same as the distance between centres of main and front drivers. The point of suspension of the back part of the engine being thus brought forward, a greater proportion of the total weight is carried on the drivers and rendered available for adhesion, and the tractive power of the hard coal burner is accordingly somewhat greater than that of the soft coal engine. The rigid wheel-base of the hard coal burner is also lessened from 17 to 24 inches by the same modification. CURVING. All engines of this Division are built with a swing-bolster truck. The middle pair of drivers have tires without flanges. The engine is accordingly guided on the rails by the truck and the flanges of the front driving-wheels, and is found to pass curves without difficulty. If preferred, however, the front instead of the main pair of drivers can have the plain tires. Both methods are in use. STRAIGHT AND WAGON-TOP BOILERS. All the engines of this Division are built with wagon-top boilers or with straight boilers and two domes, as preferred. Where the latter form is made, the throttle-valve is placed in the forward dome. The wagon-top and straight boilers for the same class are so proportioned as to give equal steam space and the same number of flues in both forms of construction. [Illustration: Locomotive.] DIVISION III. FREIGHT OR PUSHING ENGINES.--"MOGUL" PATTERN. CLASS 27-1/2 D. General Design Illustrated by Print on Page 74. CYLINDERS. Diameter of cylinders 16 inches. Length of stroke 22 or 24 inches. DRIVING-WHEELS. REAR AND FRONT PAIRS WITH FLANGED TIRES 5-1/2 INCHES WIDE. MAIN PAIR WITH PLAIN TIRES 6 INCHES WIDE. Diameter of drivers 48 to 54 inches. TRUCK. ONE PAIR OF LEADING WHEELS, WITH SWING BOLSTER AND RADIUS-BAR, EQUALIZED WITH FRONT DRIVERS. Diameter of wheels 30 inches. WHEEL-BASE. Total wheel-base 21 ft. 4 inches. Rigid " (distance between centres of rear and front drivers) 14 ft. TENDER. ON TWO FOUR-WHEELED TRUCKS. Capacity of tank 1600 gallons. WEIGHT OF ENGINE IN WORKING ORDER. On drivers 57,000 pounds. On leading wheels 9,000 " ------ Total weight of engine, about 66,000 "