the next standing still. This was on account of the engine being
only in power one half of the stroke; but by the double-acting engine
being introduced, and the steam acting both ways, it became at last a
steady mover (without the aid of two or three cylinders, as in the first
engines, one to take up the other as the power was given off), by a
ratchet on the end of a beam or else a chain. This acted on the shaft
which moved the paddles. It is to Watt that we are indebted for the
crank and direct action, so as to give a circular motion to the wheels.

We find in 1752 a Mr. Champion of Bristol applied the atmospheric engine
to raise water to drive a number of wheels for working machinery in a
brasswork, in other words, a foundry. Also, in Colebrokedale,
steam-engines were used to raise water that had passed over the wheel,
so as to save water. All these plans have, however, now passed by, like
the water over the wheel, and we now have the engine the prime
mover--the double action of the steam on the piston, this acting on the
sway beam, and the beam on the crank, which, by the assistance of the
fly-wheel on land or fixed engines, gives a uniform motion to the
machine. All these have now enabled us to apply the engine as our grand
moving power. One great and important point in the engine is the
governor, and the first modes of changing the steam from the top to the
bottom of the cylinder were cumbrous, till the excentric wheel was
devised.

Boilers also have to be attended to--these were at first rude and now
would be useless. They were unprovided with valves, gauge-cocks, or any
other safety, all of which are now so well understood that nothing but
carelessness can cause a blow-up. One of the greatest causes of danger
is that of letting there be too little water in the boiler, and thus
allowing it to get red-hot, when, if you let in water, such a volume of
steam is generated that no valve will let it escape fast enough. Force
or feed pumps are also required to keep the water in the boiler at a
proper height, which is ascertained by the gauge-cocks. Mercury gauges
for low pressure act according to the pressure of the atmosphere;
high-pressure boilers of course require a different construction, as the
steam is greater in pressure than the air.

Having got so far in my subject, I think before concluding I must devote
a short time in showing the first steps of the locomotive; the more so,
as I am speaking to those who are