_Third_.--The general convenience of subdividing the work to be done,
so that in case of a stoppage of one portion of the work by reason of
a loose coupling or the changing of a pulley, etc., that portion only
would need to be stopped.

This last is of itself a most important point, and demands careful
consideration.

For example, I was at a mill a short time ago when the governor belt
broke. The result was a stoppage of the whole mill. Had the motive power
of this mill been subdivided into a number of small engines only one
department would have been stopped. During the stoppage in this case
the windows of the mill were a sea of heads of men and women (the
operatives), and considerable excitement was caused by the violent
blowing off of steam from the safety-valves, due to the stoppage of the
steam supply to the engine; and this excitement continued until the
cause of the stoppage was understood. Had the power in this mill been
subdivided the stoppage of one of a number of engines would scarcely
have been noticed, and the blowing off of surplus steam would not have
occurred.

In building a mill the first item to be considered is the interest on
the first cost of the engine, boilers, etc. This item can be subdivided
with advantage into the amounts of interest on the respective costs of,

_First_. The engine or engines;

_Second_ The boiler or boilers;

_Third_. The engine and boiler house.