contrivance, the governor of the steam-engine, which must
immediately occur to all who are familiar with that admirable
engine. Wherever the increased speed of the engine would lead to
injurious or dangerous consequences, this is applied; and it is
equally the regulator of the water-wheel which drives a
spinning-jenny, or of the windmills which drain our fens. In the
dockyard at Chatham, the descending motion of a large platform,
on which timber is raised, is regulated by a governor; but as the
weight is very considerable, the velocity of this governor is
still further checked by causing its motion to take place in
water.

28. Another very beautiful contrivance for regulating the
number of strokes made by a steam-engine, is used in Cornwall: it
is called the cataract, and depends on the time required to fill
a vessel plunged in water, the opening of the valve through which
the fluid is admitted being adjustable at the will of the
engine-man.

29. The regularity of the supply of fuel to the fire under
the boilers of steam-engines is another mode of contributing to
the uniformity of their rate, and also economizes the consumption
of coal. Several patents have been taken out for methods of
regulating this supply: the general principle being to make the
engine supply the fire with small quantities of fuel at regular
intervals by means of a hopper, and to make it diminish this
supply when the engine works too quickly. One of the incidental
advantages of this plan is, that by throwing on a very small
quantity of coal at a time, the smoke is almost entirely
consumed. The dampers of ashpits and chimneys are also, in some