Newhaven, another between Greenwich and Woolwich, another at
Northfleet, and in many other places. Indeed, such mills were used
pretty extensively; they were generally erected at the mouth of a
stream, and in that way the river bed made the reservoir, and even
when they were erected in other situations, those were of a kind
suitable for the purpose, that is, lowlying lands were selected, and
were embanked to form reservoirs. In 1881, windmills and water-wheels
are much the same, but the turbines are greatly improved, and by means
of turbines we are enabled to make available the pressure derived from
heads of water which formerly could not be used at all, or if used,
involved the erection of enormous water-wheels, such as those at
Glasgow and in the Isle of Man, wheels of some eighty feet in
diameter. But now, by means of a small turbine, an excellent effect is
produced from high heads of water. The same effect is obtained from
the water-engines which our president has employed with such great
success. In addition to these motors, we have the gas-engine, which,
within the last few years only, has become a really useful working and
economical machine. With respect to horse-power motors, we have not
only the old horse engines, but we have a new application, as it seems
to me, of the work of the horse as a motor. I allude to those cases
where the horse drawing a reaping or thrashing machine, not only pulls
it forward as he might pull a cart, but causes its machinery to
revolve, so as to perform the desired kind of work. This species of
horse-engine, though known, was but little used in 1831. With respect
to hot-air engines there have been many attempts to improve them, and
some hot-air engines are working, and are working with considerable
success; but the amount of power they develop in relation to their
size is small, and I am inclined to doubt whether it can be much
increased.