But, in consequence of the division of labour, the whole of every man's
attention comes naturally to be directed towards some one very simple
object. It is naturally to be expected, therefore, that some one or other of
those who are employed in each particular branch of labour should soon find
out easier and readier methods of performing their own particular work,
whenever the nature of it admits of such improvement. A great part of the
machines made use of in those manufactures in which labour is most
subdivided, were originally the invention of common workmen, who, being each
of them employed in some very simple operation, naturally turned their
thoughts towards finding out easier and readier methods of performing it.
Whoever has been much accustomed to visit such manufactures, must frequently
have been shewn very pretty machines, which were the inventions of such
workmen, in order to facilitate and quicken their own particular part of the
work. In the first fire engines {this was the current designation for steam
engines}, a boy was constantly employed to open and shut alternately the
communication between the boiler and the cylinder, according as the piston
either ascended or descended. One of those boys, who loved to play with his
companions, observed that, by tying a string from the handle of the valve
which opened this communication to another part of the machine, the valve
would open and shut without his assistance, and leave him at liberty to
divert himself with his play-fellows. One of the greatest improvements that
has been made upon this machine, since it was first invented, was in this
manner the discovery of a boy who wanted to save his own labour.

All the improvements in machinery, however, have by no means been the
inventions of those who had occasion to use the machines. Many improvements
have been made by the ingenuity of the makers of the machines, when to make
them became the business of a peculiar trade; and some by that of those who
are called philosophers, or men of speculation, whose trade it is not to do
any thing, but to observe every thing, and who, upon that account, are often