IN ADDITION TO ENGINE AND TENDER. On a level 1075 gross tons. " 20 ft. grade 495 " " " 40 " 310 " " " 60 " 220 " " " 80 " 165 " " " 100 " 130 " " The distance between centres of drivers (rigid wheel-base) can be made 8 ft. 6 in., if preferred to 8 ft. as given above. This greater spread of wheels, throwing more weight on the drivers, gives the engine greater adhesion, and thus adds to its efficiency for freight service. Owing to the peculiar construction of the truck, the engine is found to pass short curves without difficulty, even with this greater distance between driving-wheel-centres. ADDENDA. ADAPTATION FOR EITHER PASSENGER OR FREIGHT SERVICE. The five preceding classes, embracing road locomotives with cylinders from thirteen to seventeen inches in diameter, admit of construction with either a twenty-two or a twenty-four inches stroke, and with driving-wheels of any diameter from fifty-six to sixty-six inches. Each class can, therefore, be adapted to either passenger or freight service, by giving the shorter stroke and the larger wheel for the former use, and the longer stroke and smaller wheel for the latter. The same cylinder pattern is used for both the twenty-two and the twenty-four inches stroke, the difference in length being made by recessing the cylinder heads. ANTHRACITE COAL BURNERS. The illustrations and figures given for engines in this Division are all for soft coal or wood burners. For anthracite coal the form of the furnace is changed, giving a longer grate and shallower fire-box. The barrel of boiler, length of connecting-rods, number and length of flues, etc., remain the same, so that no change in principal patterns results. The change in shape and dimensions of fire-box, however, alters the distribution of weight, throwing more load on the drivers and less on the truck, while the total weight of engine remains nearly the same. The hard coal burners, accordingly, having from this cause somewhat more adhesion than the soft coal burners of the same class, have proportionately more tractive power, and will haul loads from ten to fifteen per cent. greater than those given for the corresponding soft coal or wood burning engines. 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 II. TEN-WHEELED FREIGHT LOCOMOTIVES. CLASS 24-1/2 D.