for each day was translated into foot-pounds of energy, and to our
surprise we found that there was no constant or uniform relation between
the foot-pounds of energy which the man exerted during a day and the
tiring effect of his work. On some kinds of work the man would be tired
out when doing perhaps not more than one-eighth of a horse-power, while
in others he would be tired to no greater extent by doing half a
horse-power of work.

We failed, therefore, to find any law which was an accurate guide to the
maximum day's work for a first-class workman.

A large amount of very valuable data had been obtained, which enabled us
to know, for many kinds of labor, what was a proper day's work. It did
not seem wise, however, at this time to spend any more money in trying
to find the exact law which we were after. Some years later, when more
money was available for this purpose, a second series of experiments was
made, similar to the first, but some what more thorough.

This, however, resulted as the first experiments, in obtaining valuable
information but not in the development of a law. Again, some years
later, a third series of experiments was made, and this time no trouble
was spared in our endeavor to make the work thorough. Every minute
element which could in anyway affect the problem was carefully noted and
studied, and two college men devoted about three months to the
experiments. After this data was again translated into foot-pounds of
energy exerted for each man each day, it became perfectly clear that
there is no direct relation between the horse-power which a man
exerts (that is, his foot-pounds of energy per day) and the tiring effect
of the work on the man. The writer, however, was quite as firmly
convinced as ever that some definite, clear-cut law existed as to what