private
performances of the engine, and were greatly pleased with it. Writing to
a Cornish friend shortly after its arrival in town, Sir Humphry said: "I
shall soon hope to hear that the roads of England are the haunts of
Captain Trevithick's dragons--a characteristic name." The machine was
afterwards publicly exhibited in an enclosed piece of ground near Euston
Square, where the London and North-Western Station now stands, and it
dragged behind it a wheel-carriage full of passengers. On the second day
of the performance, crowds flocked to see it; but Trevithick, in one of
his odd freaks, shut up the place, and shortly after removed the engine.
It is, however, probable that the inventor came to the conclusion that
the state of the roads at that time was such as to preclude its coming
into general use for purposes of ordinary traffic.

While the steam-carriage was being exhibited, a gentleman was laying
heavy wagers as to the weight which could be hauled by a single horse on
the Wandsworth and Croydon iron tramway; and the number and weight of
waggons drawn by the horse were something surprising. Trevithick very
probably put the two things together--the steam-horse and the
iron-way--and kept the performance in mind when he proceeded to construct
his second or railway locomotive. The idea was not, however, entirely
new to him; for, although his first engine had been constructed with a
view to its employment upon common roads, the specification of his patent
distinctly alludes to the application of his engine to travelling on
railroads. Having been employed at the iron-works of Pen-y-darran, in
South Wales, to erect a forge engine for the Company, a convenient
opportunity presented itself, on the completion of this work, for
carrying out his design of a locomotive to haul the minerals along the
Pen-y-darran tramway. Such an engine was erected by him in 1803, in the
blacksmiths' shop at the Company's works, and it was finished and ready
for trial before the end of the year.

The boiler of this second engine was cylindrical in form, flat at the
ends, and made of wrought iron. The furnace and flue were inside the
boiler, within which the single cylinder, eight inches in diameter and
four feet six inches stroke, was placed horizontally. As in the first
engine, the motion of the wheels was produced by spur gear, to which was
also added a fly-wheel on one side, to secure a rotatory motion in the
crank at the end of ea