The first means in the earliest times of steam engineering, for opening
and shutting the passages in the pipes of steam engines were cocks
and these were all worked by hand and required close attention. A boy
named Humphry Potter being in charge of one of the cocks of Newcomen’s
pumping-engines, and desiring time for play, it is said, managed to
fasten the lever-handles of the spigots by means of rods and string
to the walking beam of the engine, so that each recurrent motion of
the beam effected the change required. This was the first automatic
valve-motion.
[Illustration: Fig. 150.]
[Illustration: Fig. 151.]
[Illustration: Fig. 152.]