The engine, when in operation, must not exceed three and one-half tons weight, and must, on a level road, be capable of drawing day by day fifteen tons, inclusive of the weight of wagons, fifteen miles per hour.
In pursuance of this call upon American genius, three locomotives were produced, but only one of these was made to answer any useful purpose. This engine, the "York," was built at York, Pa., and was brought to Baltimore over the turnpike on wagons. It was built by Davis & Gartner, and was designed by Phineas Davis, of that firm, whose trade and business was that of a watch and clock maker. After undergoing certain modifications, it was found capable of performing what was required by the company. After thoroughly testing this engine, Mr. Davis built others, which were the progenitors of the "grasshopper" engines (Fig. 7) which were used for so many years on the Baltimore & Ohio Railroad. It is a remarkable fact that three of these are still in use on that road, and have been in continuous service for over fifty years. Probably there is no locomotive in existence which has had so long an active life.
Fig. 7.—"Grasshopper" Locomotive. (From an old photograph.)
In August, 1831, the locomotive "John Bull," which was built by George & Robert Stephenson & Company, of Newcastle-upon-Tyne, was received in Philadelphia, for the Camden & Amboy Railroad & Transportation Company. This is the old engine which was exhibited by the Pennsylvania Railroad Company at the Centennial Exhibition in 1876. After the arrival of the "John Bull" a very considerable number of locomotives which were built by the Stephensons were imported from England. Most of them were probably of what was known as the "Planet" class (Fig. 8), which was a form of engine that succeeded the famous "Rocket."
The following quotation is from "The Early History of Locomotives in this Country," issued by the Rogers Locomotive & Machine Works:
These locomotives, which were imported from England, doubtless to a very considerable extent, furnished the types and patterns from which those which were afterward built here were fashioned. But American designs very soon began to depart from their British prototypes, and a process of adaptation to the existing conditions of the railroads in this country followed, which afterward "differentiated" the American locomotives more and more from those built in Great Britain. A marked feature of difference between American and English locomotives has been the use of a "truck" under the former.
Fig. 8.—The "Planet."
In all of the locomotives which have been illustrated, excepting the "South Carolina," the axles were held by the frames so that the former were always parallel to each other. In going around curves, therefore, there was somewhat the same difficulty that there would be in turning a corner with an ordinary wagon if both its axles were held parallel, and the front one could not turn on the kingbolt. The plan of the wheels and running gear of the "South Carolina" shows the position that they assumed on a curved track (Fig. 5). It will be seen that, by reason of their connection to the boiler by kingbolts, K K′, the two pairs of wheels could adjust themselves to the curvature of the rails. This principle was afterward applied to cars, and nearly all the rolling-stock in this country is now constructed on this plan, which was proposed by Mr. Allen in a report dated May 16, 1831, made to the South Carolina Canal & Railroad Company; and an engine constructed on this principle was completed the same year.