of our work."

[Sidenote: _Marvelous Increased Efficiency Handling "Pig"_]

Progress in mental efficiency must result from the application of
knowledge of the mental machine. Just as we watch the steam-engine and
the electric motor to see that they are not "overloaded," so we must
watch the mental machine, that no more power be turned on than can be
profitably employed.

This principle has already been applied to physical labor by Mr.
Frederick W. Taylor in his ground-breaking studies in "scientific
management." Mr. Taylor's celebrated experiments in the handling of
pig-iron, by which the quantity handled in a day by one man was
increased from twelve and one-half tons to forty-seven and one-half
tons, "showed that a man engaged in such extremely heavy work could
only be under load forty-three per cent of the working day, and must
be entirely free from load for fifty-seven per cent, to attain the
maximum efficiency."

[Sidenote: _"Overloaded" Human Engines_]

There is no reason why efficiency in mental effort should not be
gauged just as accurately as in muscular activity. If there are times
when your wits are not as keen, when you have not the same grasp of
fundamentals, as at other times, it is because you are mentally
"overloaded." It may be the result of a great variety of causes. It
may be from too many hours of continuous mental effort. But the
probabilities are that it is the result of vexation, worry,
dissipation, or allowing the mind to be burdened with the strain of