These new giants are, in operation, two 8-wheel engines, with individual cylinders, steam chests and supplies from a single boiler and fire-box. The gripping power of 16 driving-wheels under the enormous weight of 223 tons can be imagined; the designers estimate it at the high figure of forty-three tons. The exceptional length of these monster engines--a fraction over ninety feet--is carried around the curves of mountainous lines by an ingenious joint in their solid steel frames. This then is only the latest of American engines; but not quite the biggest, for the Topeka shops of the Santa Fe Railroad claim that honor with their new Mallets, each 121 feet long and weighing complete 810,000 pounds. The 500-ton locomotive does not seem so very far away when one comes to consider the Santa Fe giants. These engines, which are operated in pushing freights over the heavy grades in the Southwest, were built from two of the Santa Fe's heaviest freight engines. They operate with equal facility in either direction as there is not a turntable in the land which would come anywhere near accommodating them. [Illustration: ONE OF THE "DIAMOND-STACK" LOCOMOTIVES USED ON THE PENNSYLVANIA RAILROAD IN THE EARLY SEVENTIES PRAIRIE TYPE PASSENGER LOCOMOTIVE OF THE LAKE SHORE PACIFIC TYPE PASSENGER LOCOMOTIVE OF THE NEW YORK CENTRAL ATLANTIC TYPE PASSENGER LOCOMOTIVE, BUILT BY THE PENNSYLVANIA RAILROAD AT ITS ALTOONA SHOPS] [Illustration: ONE OF THE GREAT MALLET PUSHING ENGINES OF THE DELAWARE & HUDSON COMPANY A TEN-WHEELED SWITCHING LOCOMOTIVE OF THE LAKE SHORE SUBURBAN PASSENGER LOCOMOTIVE OF THE NEW YORK CENTRAL CONSOLIDATION FREIGHT LOCOMOTIVE OF THE PENNSYLVANIA] In recent years, the rather graceful custom of giving names to the classification of locomotives has been extended to the passenger motive-power. In 1895, the Baldwins created the Atlantic type of four-driver locomotive for high-speed service both on the Atlantic Coast Line and on the Atlantic City Railroad, from Camden to the ocean--and the name has stuck. The Brooks plant of the American Locomotive Company at Dunkirk similarly developed the Pacific type for passenger locomotives with six drivers instead of four. The Prairie type was appropriately enough sponsored by the Burlington system. It is like the Pacific type save that the forward or lead truck (the Englishman would blandly call it the "bogey") has but two instead of the conventional four wheels.