I have spoken of rest through change of work. But the change ought to be such as sets free imprisoned, unused faculties that find no outlet in our daily work. It may be that marriages are made in heaven, but the marriage of a man to his job is very seldom made in heaven, and so mismating is common. The whole human race is too big for its jobs. The industrial system is altogether too small to fit us;--a large part of our powers remain unused. Therefore, the purpose of our time for rest and recreation, our evenings and our Sundays, should be to even up that balance, to use the part of us that is not used at other times. Sunday ought to be a family day, just because in the working world people do not see much of their families during the week; it ought to be a day in the country because we have organized these things called cities and live in them during the week. It ought to be a day of worship because we forget our religion so much in the week's work. Everything that we do on Sundays ought to be an evening-up of what gets crowded out of our week-day lives. _Tests of fatigue_ The English tests of fatigue are nowhere near being applied yet in America or anywhere else as we hope some day they will be, to solve this tremendous problem of industrial fatigue and industrial disease. In some of the ammunition works in England[3] they took a body of people of approximately the same age and sex, living under the same conditions approximately, doing the same work. They changed the working hours of one set and left the other set unchanged as a "control." In any scientific test we have to have what we call a "control," something that enables us to compare the changes that we bring about experimentally with the unchanged state of things. (_a_) In one room the hours of labor were left unmodified, in the other modified, first increased, then decreased. They made interesting experiments to see whether a man produced as much output, in eight hours as he could in ten; they showed that he could produce as much in the shorter time as he could in the longer time, presumably because he was less tired, less bored, less strained. They made a further cut and found that then he did not produce as much. There is a limit, therefore. He could not probably produce as much in four as in eight hours. Then they experimented on continuity and discontinuity of work--whether a person could produce as much or more in five continuous hours as in two batches of two and a half hours with rest in between. They found that the shorter periods did distinctly better. Output, then, was the first rough, but still serviceable, test that they used in relation to fatigue. (_b_) Next they recorded the general look and feeling of the men as the foreman and other interested people could size it up--the look of listlessness, of boredness, of fatigue in the working-man when they varied the hours and continuity of work in the ways that I have spoken of.