The National Museum’s nonoperable model shown in figure 61 represents
the probable form of the first rail locomotive of Richard Trevithick,
the Cornish engineer who was one of the early advocates of the
high-pressure steam engine. The Museum’s model (USNM 180058) is about 20
inches in length, and its flywheel is about 10 inches in diameter. It
was obtained in 1888 from its builder D. Ballauf, a model maker often
employed by the Museum.
[Illustration: Figure 61.—Model of Trevithick locomotive, 1804.]
Trevithick, who a few years earlier had constructed several successful
steam vehicles for use on the highways, in February 1804 completed the
construction of a machine at Pen-y-darran, near Merthyr Tydfil,
Glamorganshire, Wales, for use at the Pen-y-darran Iron Works of Samuel
Homfray. It is thought to have been the first steam locomotive ever
propelled along a railway.
The first trip was made on Monday, February 13, 1804. Among the several
trips made by the locomotive was one of 9 miles, between Merthyr Tydfil
and Abercynon, drawing 5 cars with a load of 10 tons of iron and 70 men.
Although a satisfactory machine, and one that proved that a useful load
could be hauled through the adhesion of wheels on smooth track, it was
not long in use because of frequent breakage of the primitive railway.
The single horizontal steam cylinder, projecting partly into the end of
the boiler, operated a crankshaft fitted with a large-diameter flywheel.
The driving wheels were coupled to the crankshaft by gearing. The bore
and stroke of the cylinder are said to have been about 8¼ and 54 inches,
respectively, and the unflanged wheels were about 45 inches in diameter.
Discharge of the exhaust steam into the chimney was utilized with this
particular locomotive, as Trevithick appreciated fully the effect it had
upon the fire. The date of this early use of exhaust steam to aid the
fire greatly antedates those claimed for later locomotive builders.