_side levers_. One of these
side levers is seen in full view in the engraving. It is the massive
flat beam, marked L, near the fore-ground of the view. It turns upon an
enormous pivot which passes through the centre of it, as seen in the
drawing, in such a manner that when the cylinder end is drawn up by the
lifting of the cross head, the other end is borne down to the same
extent, and with the same prodigious force. There is another side beam,
on the other side of the cylinder, which moves isochronously with the
one in view. The forward end of this other beam may be seen, though the
main body of it is concealed from view. These two forward ends of the
levers are connected by a heavy bar, called the _cross tail_, which
passes across from one to the other. From the centre of this cross tail,
a bar called the connecting rod rises to the crank, where the force
exerted by the steam in the cylinders is finally expended in turning the
great paddle wheels by means of the main shaft, S, which is seen resting
in the pillow block, P, above. These are the essential parts of the
engine, and we now proceed to consider the mode of manufacturing these
several parts, somewhat in detail.

[Illustration: THE CUTTING ENGINE.]

The boilers are formed of wrought iron. The material is previously
rolled into plates of the requisite thickness, and then the first part
of the process of forming these plates into a boiler is to cut them into
proper forms. The monster that fulfills the function of shears for this
purpose, bears a very slight resemblance to any ordinary cutting
implement It resembles, on the other hand, as represented in the
adjoining engraving, an enormous letter U, standing perpendicularly upon
one of its edges. Through the centre of the upper branch of it there
passes a shaft or axle, which is turned by the wheels and machinery
behind it, and which itself works the cutter at the outer end of it by
means of an eccentric wheel. This cutter may be seen just protruding
from its place, upon the plate which the workmen are holding underneath.
The iron plates thus presented are sometimes nearly half an inch thick,
but the monstrous jaw of the engine, though it glides up and down when
there is nothing beneath it in the most gentle and quiet manner
possible, cuts them through, as if they were plates of wax, and
apparently without feeling the obstruction.

[Illustration: THE BENDING AND PUNCHING ENGINES.]

The plates, when cut, are t