ing-press must
take high rank, and this we owe entirely to Watt.

Of the same period as the copying-machine is his invention of a
drying-machine for cloth, consisting of three cylinders of copper over
which the cloth must turn over and under while cylinders are filled with
steam, the cloth to be alternately wound off and on the two wooden
rollers, by which means it will pass over three cylinders in
succession. This machine was erected for Watt's father-in-law, Mr.
MacGregor in Glasgow, by an ingenious mechanic, John Gardiner, often
employed by Watt in earlier years. "This I apprehend," he writes to
David Brewster in 1814, "to be the original from which such machines
were made." When we consider the extent to which such steam
drying-machines are used in our day, our estimate of the credit due to
Watt cannot be small. The drying-machine is no unfit companion to the
copying-machine.

Watt revisited Cornwall in 1781 to make an inspection of all the
engines. Much he found needing attention and improvement. His evenings
were spent designing "road steam-carriages." This was before the day of
railroads, and the carriages were to be driven by steam over the
ordinary coach roads. He filled a quarto drawing-book with different
plans for these, and covered the idea in one of his patent
specifications. Boulton suggested in 1781 that the idea of rotary motion
should be developed, which Watt had from the first regarded as of prime
importance. It was for this he had invented his original wheel engine,
and in his first patent of 1769 he describes one method of securing it.
It occurred to him that the ordinary engine might be adapted to give the
rotary motion. He wrote from Cornwall to Boulton: "As to the circular
motion, I will apply it as soon as I can." He prepared a model upon his
return to Soho, using a crank connected with the working-beam of the
engine for that purpose, which worked satisfactorily. There was nothing
new in the crank motion; it was used on every spinning-wheel,
grind-stone and foot-lathe turned by hand, but its application to the
steam-engine was new. As early as 1771, he writes:

I have at times had my thoughts a good deal upon the subject. In
general, it appears to me that a crank of a sufficient sweep
will be by much the sweetest motion, and perhaps not the
dearest, if its durability be considered ... I then resolved to
adopt the crank ... Of this I caused a model to be made, which
pe