cylinders fourteen by twenty, and six-feet driving-wheels, the "Mifflin," "Blair," and "Indiana," were also built for the Pennsylvania Railroad Company, in 1849. They weighed each about forty-seven thousand pounds, distributed as follows: eighteen thousand on drivers, fourteen thousand on the pair of wheels in front of the fire-box, and fifteen thousand on the truck. By applying the lever, the weight on the drivers could be increased to about twenty-four thousand pounds, the weight on the wheels in front of the fire-box being correspondingly reduced. A speed of four miles in three minutes is recorded for them, and upon one occasion President Taylor was taken in a special train over the road by one of these machines at a speed of sixty miles an hour. One other engine of this pattern, the "Susquehanna," was built for the Hudson River Railroad Company, in 1850. Its cylinders were fifteen inches diameter by twenty inches stroke, and drivers six feet in diameter. All these engines, however, were short-lived, and died young, of insufficient adhesion. Eight engines with four drivers connected and half-crank-axles, were built for the New York and Erie Railroad Company in 1849, with seventeen by twenty inch cylinders; one-half of the number with six-feet and the rest with five-feet drivers. These machines were among the last on which the half-crank-axle was used. Thereafter, outside-connected engines were constructed almost exclusively. In May, 1848, Mr. Baldwin filed a caveat for a four-cylinder locomotive, but never carried the design into execution. The first instance of the use of steel axles in the practice of the establishment occurred during the same year,--a set being placed as an experiment under an engine constructed for the Pennsylvania Railroad Company. In 1850, the old form of dome boiler, which had characterized the Baldwin engine since 1834, was abandoned, and the wagon-top form substituted. The business in 1851 had reached the full capacity of the shop, and the next year marked the completion of about an equal number of engines (forty-nine). Contracts for work extended a year ahead, and, to meet the demand, the facilities in the various departments were increased, and resulted in the construction of sixty engines in 1853, and sixty-two in 1854. At the beginning of the latter year, Mr. Matthew Baird, who had been connected with the works since 1836 as one of its foremen, entered into partnership with Mr. Baldwin, and the style of the firm was made M. W. Baldwin & Co.