on is by far more complicated, and the often
capricious changes in the plant have very little in common with a
systematic experiment. Some well-known studies of the efficiency
engineers clearly demonstrate the possibility of such systematic
efforts. The best-known case is probably Taylor's study of the
pig-iron handlers of the Bethlehem Steel Company. He found that the
gang of 75 men was loading on the average about 12-1/2 tons per man
per day. When he discussed with various managers the question of what
output would be the possible maximum, they agreed that under premium
work, piecework, or any of the ordinary plans for stimulating the men,
an output of 18 to 25 tons would be the extreme possibility. Then he
proceeded to a systematic study of the fatigue in its relation to the
burden and of the best possible relation between working time and
resting time. His first efforts to find formulas were unsuccessful,
because he calculated only the actual mechanical energy exerted and
found that some men were tired after exerting energy of 1/8 hp., while
others seemed to be able to produce the energy of 1/2 hp. without
greater fatigue. But soon he discovered the mistake in his figures.
He had considered only the actual movements, and had neglected the
period in which the laborer was not moving and was not exerting
energy, but in which a weight was pulling his arms and demanding a
corresponding muscular effort. As soon as this muscular achievement
was taken into account, too, he found that for each particular weight
a definite relation exists between the time that a man is under a
heavy load and the time of rest. For the usual loads of 90 pounds, he
found that a first-class laborer must not work more than 43 per cent
of time working day and must be entirely without load 57 per cent. If
the load becomes lighter, the relation is changed. If the workman is
handling a half pig weighing 46 pounds, he can be under load 58 per
cent of the day and only has to rest during 42 per cent.[43]

As soon as these figures were experimentally secured, Taylor selected
fit men, and did not allow them to lift and to carry the loads as they
pleased, but every movement was exactly prescribed by foremen who
timed exactly the periods of work and rest. If he had simply promised
his men a high premium in case they should carry more than the usual
12 tons a day, they would have burdened themselves as heavily as
possible and would have carried the load as qu