A small nonoperable model of the _Tom Thumb_, about 2 feet long (figure 16), made in the National Museum in 1890 (USNM 204581), is exhibited in the collection of the Museum. Other small models of it appear in the B & O Museum. One of these, a ¼-inch-scale model recently made under the direction of Lawrence W. Sagle of the B & O Museum, differs somewhat from the usually accepted idea of the _Tom Thumb_. Notably, the smokestack is not straight, but has an elbow at its upper end, and the belt-driven blower is located there rather than on the floor of the machine as in the replica and the other models. Peter Cooper, the New York engineer and inventor who constructed the original _Tom Thumb_ as an experiment in the winter of 1829-1830, mentioned this upper location of the blower in a speech delivered many years later, in 1875, and quoted in Bulletin 73 of the Railway and Locomotive Historical Society (1948, pp. 50-52). The little locomotive, with its vertical boiler made of rifle barrels, looked rather like the larger locomotive of John Stevens of only several years earlier but had considerably smaller wheels, these being only 30 inches in diameter. Although a 3¼-inch bore for its vertical 1-cylinder engine is given by most writers, Jonathan Knight, chief engineer of the Baltimore and Ohio, in the fourth annual report of the company (for 1830, p. 35) gives the figure as 3½. Unfortunately, he does not mention the stroke, which is usually given elsewhere as either 14¼ or 14½ inches. The bore and stroke of the replica were made 5 and 27 inches so as to give it sufficient power to operate satisfactorily. For that matter, in the interest of sturdiness and suitable operation the replica is somewhat larger in all respects and considerably heavier than the original. It operates on a steam pressure of 90 pounds per square inch, and it is reported that the original did likewise. [Illustration: Figure 15.—Full sized operable replica of Cooper’s _Tom Thumb_, built in 1926 by Baltimore and Ohio Railroad Co. (PETER COOPER’S “TOM THUMB” 1829-30 BALTIMORE & OHIO R.R.)] [Illustration: Figure 16.—Model of _Tom Thumb_, in National Museum.] The _Tom Thumb_ was engaged in its famous race with the horse-drawn railroad car in the summer of 1830 on a parallel section of the new 13-mile stretch of track between Baltimore and Ellicott’s Mills. It covered the 13 miles between the Mount Clare station and Ellicott’s Mills in a little over an hour, and the return trip in 57 minutes. The race with the horse-drawn car took place during the return trip. The _Tom Thumb_ appeared to be a certain winner until temporary slipping of the belt driving the blower caused the steam pressure to drop and allowed the horse to become the victor.