In a letter to Askew (Dec. 14, 1922) the chief of motive power of the Pennsylvania System, J. T. Wallis, stated that the cylinders of the original had a bore and stroke of 22 and 26 inches. The drivers were 80 inches in diameter and the boiler carried a steam pressure of 205 pounds. The boiler had a minimum (internal) diameter of 65½ inches, and it contained 170 2-inch flues and 24 5½-inch flues, while the superheater consisted of 96 1½-inch flues. The distance between flue sheets was 180 inches and the total heating surface was 2,571 square feet. The grate was 111 inches long and 72 wide. The total weight on the drivers was 127,200 pounds, on the engine truck 35,500 pounds, and on the trailer truck 33,900 pounds—or a total of 196,600 pounds in working order. The weight of the tender in working order was 134,000 pounds. The tractive force of the locomotive was 27,409 pounds. In his letter Wallis also made the following statement to explain the significance of the modification of this class of locomotive: The Atlantic, or 4-4-2, type locomotive was developed in an effort to retain the desirable features of the American, or 4-4-0, type of locomotive and at the same time to produce a locomotive in answer to the demand for greater power. To do this, the firebox was increased in area by making it considerably wider, so that a greater amount of soft coal could be burned. The diameter of the barrel of the boiler was increased to allow for greater heating surface, which, of course, increased the weight on the drivers. To make room for the driving wheels without unduly increasing the length of the tubes in the boiler, the driving wheels were moved forward, the main driver being in the rear instead of in front as in the American type locomotive. In order to carry the weight of the firebox, which, with the new driving wheel location, overhangs the rear driver too much to be properly supported, a two-wheel trailer truck was used. This trailer truck, which is fulcrumed a short distance back of the main driver, is so designed that it has lateral motion, and provision is made for ash pan as well as firebox clearance. By the use of higher steam pressure, larger heating surface and grate area, the use of passenger locomotives of the three-coupled type, with the troubles incident to the use of long parallel rods, was put off for a decade. General Electric Locomotive, 1926 A detailed and exquisitely made operable model of the New York Central class T-3A electric locomotive _No. 1173_, now _No. 273_, was constructed by W. Howard R. Parsons, and was donated by him in 1952 to the Museum (USNM 314237).