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.

Another experiment was made out of doors, on which occasion, small
though the engine was, it fairly outran the speed of its inventor. One
night, after returning from his duties at the mine at Redruth, Murdock
went with his model locomotive to the avenue leading to the church,
about a mile from the town. The walk was narrow, straight, and level.
Having lit the lamp, the water soon boiled, and off started the engine
with the inventor after it. Shortly after he heard distant shouts of
terror. It was too dark to perceive objects, but he found, on
following up the machine, that the cries had proceeded from the worthy
vicar, who, while going along the walk, had met the hissing and fiery
little monster, which he declared he took to be the Evil One in propria
persona!

When Watt was informed of Murdock's experiments, he feared that they
might interfere with his regular duties, and advised their
discontinuance. Should Murdock still resolve to continue them, Watt
urged his partner Boulton, then in Cornwall, that, rather than lose
Murdock's services, they should advance him 100L.; and, if he succeeded
within a year in making an engine capable of drawing a post-chaise
carrying two passengers and the driver, at the rate of four miles an
hour, that a locomotive engine business should be established, with
Murdock as