The life of George Stephenson, railway engineer - Lighthouse ...

CHAP. XXXV.] HIS LAST IMPROVEMENT IN THE LOCOMOTIVE. 431
which he had originated. Thus, in 1846, he brought out his
design of a three-cyhnder locomotive,—the two outside cyhnders
acting together in the same plane, the third cylinder, with a
crank in the middle of the axle, acting at right angles to the
plane and crank pins of the two other cylinders. The middle
cylinder was double the diameter of the others ; and its compen-
sating action neutralized the tendency to oscillate, which was a
defect in the long-boiler outside-cylinder engines as oi-iginally
constructed. Although this new engine was very ingenious,
and acted with great power, it has not come into general use, in
consequence of the somewhat greater expense of its construction
and working. The oscillation, also, of the outside-cylinder en-
gines, which this invention was designed to correct, has since
been obviated by an improvement in their design and structure.
A three-cylinder engine was, however, constructed by way of
experiment for the Northeastern Railway, on which line it
still continues in efficient work.
Shortly after, Mr. Stephenson invented a new self-acting
brake, after a plan which had occupied his attention for many
years, and which had been partially adopted on the Liverpool
and Manchester 'Railway during the time that he was its acting
engineer. He now communicated a paper on the subject, accom-
panied by a beautiful model, to the Institute of Mechanical
Engineers at Birmingham, .of which he was president. The
great recommendation of the plan was its simplicity and cheap-
ness. " Any effectual plan," he said, " for increasing the safety
of railway travelling is, in my mind, of such vital importance,
that I prefer laying my scheme open to the world to taking out
a patent for it ; and it will be a source of great pleasure to me
to know that it has been the means of saving even one human
life from destruction, or that it has prevented one serious concussion."
*
In 1847, the year before his death, Mr. Stephenson was in-
vited to join a distinguished party at Sir Robert Peel's mansion
at Drayton Manor, and to assist in the ceremony of formally
opening the Trent Valley Railway, which had been originally
« See the " Practical Mechanic's Journal," vol. i. p. 53, for a description of
the Self-acting Brake.