were scientifically determined.

Again, there is a question of the length of each rest period. It
has been proven that in many classes of work, and especially in
those where the work is interrupted periodically by reason of its
peculiar nature, or by reason of inefficient performance in one of
the same sequence of dependent operations, alternate working and
resting periods are best. There is to be considered in this
connection, however, the recognized disadvantage of reconcentrating
the attention after these rest periods. Another thing to be
considered is that the rate of output does not decline from the
beginning of the day, but rather the high point of the curve
representing rate of production is at a time somewhat later than at
the starting point. The period before the point of maximum
efficiency is known as "warming up" among ball players, and is well
recognized in all athletic sports.

As for the point of minimum efficiency, or of greatest fatigue,
this varies for "morning workers," and "night workers." This
exemplifies yet another variable.

The minuteness of the sub-fields that demand observation, is
shown by an entry in the Psychological Index: "1202. Benedict, F.G.
"Studies in Body--Temperature." 1. Influence of the Inversion of the
Daily Routine; the Temperature of Night Workers."[14]

SELECTION OF BEST UNIT OF MEASUREMENT NECESSARY AND IMPORTANT.--
Selecting the unit of measurement that will of itself reduce costs
is a most important element in obtaining maximum efficiency.[15]
This is seldom realized.[16] Where possible, several units of
measurements should be used to check each other.[17] One alone may
be misleading, or put an incentive on the workers to give an
undesirable result.

The rule is,--always select that unit of output that will, of
itself, cause a reduction in costs.

For example:--In measuring the output of a concrete gang,
counting cement bags provides an incentive to use more cement than
the instruction card calls for. Counting the batches of concrete
dumped out of the mixer, provides an incentive to use rather smaller
quantities of broken stone and sand than the proportions call
for,--and, furthermore, does not put the incentive on the men to
spill no concrete in transportation, neither does it put an
incentive to use more lumps for Cyclopean concrete.

Measuring the quantity actually placed in the forms puts no
incentive to watch bulging forms closely.