Note 5 — III. REFLECTIONS ON THE MOTIVE POWER OF HEAT, AND ON MACHINES FITTED TO DEVELOP THAT POWER.[4]

It may be said that coal-mining has increased tenfold in England since the invention of the steam-engine. It is almost equally true in regard to the mining of copper, tin, and iron. The results produced in a half-century by the steam-engine in the mines of England are to-day paralleled in the gold and silver mines of the New World—mines of which the working declined from day to day, principally on account of the insufficiency of the motors employed in the draining and the extraction of the minerals.