This first locomotive is now
to be seen at the Conservatoire des Arts et Metiers at Paris.
Murdock had doubtless heard of Watt's original speculations, and
proceeded, while at Redruth, during his leisure hours, to
construct a model locomotive after a design of his own. This
model was of small dimensions, standing little more than a foot
and a half high, though it was sufficiently large to demonstrate
the soundness of the principle on which it was constructed. It
was supported on three wheels, and carried a small copper boiler,
heated by a spirit lamp, with a flue passing obliquely through
it. The cylinder, of 3/4 inch diameter and 2-inch stroke, was
fixed in the top of the boiler, the piston-rod being connected
with the vibratory beam attached to the connecting-rod which
worked the crank of the driving-wheel. This little engine worked
by the expansive force of steam only, which was discharged into
the atmosphere after it had done its work of alternately raising
and depressing the piston in the cylinder.
Mr. Murdock's son, while living at Handsworth, informed the
present writer that this model was invented and constructed in
1781; but, after perusing the correspondence of Boulton and Watt,
we infer that it was not ready for trial until 1784. The first
experiment was made in Murdock's own house at Redruth, when the
little engine successfully hauled a model waggon round the
room,--the single wheel, placed in front of the engine and
working in a swivel frame, enabling it to run round in a circle.
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