Of this original locomotive only the boiler and safety valve remain. They are on exhibition at the National Museum (USNM 180029), where they were deposited in 1888 by the Stevens Institute of Technology. The boiler (figure 1) contains 20 wrought-iron tubes, each a little over 1 inch in outside diameter, set closely together in a circle and originally surrounding a circular grate, now missing. It is 4 feet high, including the headers, and 1 foot across, and was formerly enclosed by a jacket of thin sheet iron topped by a conical hood on which rested the smokestack. Wood used as fuel was dropped onto the grate through a door in the hood, and water was put into the boiler through a pipe in the bottom header. Steam was taken from a 1-inch pipe in the top header. The boiler when new is reported to have sustained with safety a steam pressure of 550 pounds per square inch. The design of the boiler was patented by Stevens on April 11, 1803. The safety valve (figure 2) is of simple design. It consists of a lever 10 inches long from which a 4-pound lead ball about 2½ inches in diameter is suspended. Beneath the lever, and about 1 inch in from the fulcrum, is a disk valve controlled by the weight of the ball, which hangs by a stirrup that can be moved to any of several notches, so that it can be set for different pressures at which the valve will open. [Illustration: Figure 2.—Original safety valve of Stevens’ locomotive, now in National Museum.] A small, nonoperable model of the locomotive, about 2 feet long (figure 3), was made in the National Museum in 1898 (USNM 180241) and is exhibited there. A full sized operable replica, constructed in 1928 at the Altoona shops of the Pennsylvania Railroad Co., was demonstrated (figure 4) at the Stevens Institute of Technology on November 23, 1928, upon the occasion of the inauguration of Harvey N. Davis as president of the Institute. It was given by the Pennsylvania Railroad to the Museum of Science and Industry at Chicago in 1932, where it is now exhibited. Another replica of the Stevens locomotive, made by the Pennsylvania in 1939, appeared in the railroad pageant at the New York World’s Fair in 1939 and 1940, and for a time in 1941 was exhibited at the Pennsylvania Station in New York City. In June 1941 it was placed on exhibition in the museum of Stevens Institute, where it remained until March 1943. At that time it was returned to the Pennsylvania Railroad Co., and has since been stored in their enginehouse at Trenton, N. J. [Illustration: Figure 3.—Model of Stevens’ locomotive, in National Museum. The boiler is shown outside the sheet-metal shell which normally surrounds it.] [Illustration: Figure 4.—Full sized operable replica of Stevens’ locomotive, built in 1928 by Pennsylvania Railroad Co., being demonstrated at Hoboken, N. J., on November 23, 1928.]