The steam engine familiarly explained and illustrated; with an historical sketch of its invention and progressive improvement; its applications to navigation and railways; with plain maxims for railway speculators. By the Rev. Dionysius Lardner ... With additions and notes by James Renwick ...

WATT'S SINGLE-ACTING STEAM-ENGINE. 89
reserved, keeping aloof from the world; while Mr. Bolton
was a man of address, delighting in society, active, and mixing with people of all ranks with great freedom, and without
ceremony. Had Mr. Watt searched all Europe, he probably
would not have found another person so fitted to bring his
invention before the public, in a manner worthy of its merit
and importance; and although of most opposite habits, it
fortunately so happened that no two men ever more cordially
agreed in their intercourse with each other."
The delay in the progress of the manufacture of engines
occasioned by the failure of Dr. Roebuck was such, that
Watt found that the duration of his patent would probably
expire before he would even be reimbursed the necessary
expenses attending the various arrangements for the manufacture of the engines. He therefore, with the advice and
influence of Bolton, Roebuck, and other friends, in 1775,
applied to parliament for an extension of the terms of his
patent, which was granted for 25 years from the date of his
application, so that his exclusive privilege should expire in
1800.
An engine was now erected at Soho (the name of Bolton's
factory) as a specimen for the examination of mining speculators, and the engines were beginning to come into demand.
The manner in which Watt chose to receive remuneration
from those who used his engines was as remarkable for its
ingenuity as for its fairness and liberality. He required
that one-third of the saving of coals effected by his engines,
compared with the atmospheric engines hitherto used, should
be paid to him, leaving the benefit of the other two-thirds
to the public. Accurate experiments were made to ascertain the saving of coals; and as the amount of this saving in
each engine depended on the length of time it was worked,
or rather on the number of descents of the" piston, Watt
invented a very ingenious method of determining this. The
vibrations of the great working beam were made to commu..U 2 12