The rate at which skill is acquired has been the subject of many careful studies. The results have been charted and reduced to curves, variously spoken of as ``efficiency curves,'' ``practice curves,'' ``learning curves,'' according to the nature of the task or test. Some of these dealt with the routine work of office and factory. In others typical muscular and mental activities were observed in a simpler form than could be found in actual practice. <p 223> <p 224> Five of my advanced students joined me in strenuous practice in adding columns of figures for a few minutes daily for a month. Our task was to add 765 one-place figures daily in the shortest possible time. No emphasis was placed on accuracy, but each one tried to make {illust. caption = FIG. 1.} the highest daily record for speed. The results of our practice are graphically shown in Curve A of Fig. 1. As shown in that curve for the first day our average speed was only forty-two combinations per minute, but for the thirtieth day our average was seventy-four combinations per minute, We did not quite <p 225> double our speed by the practice, and we made but little improvement in accuracy. The most rapid gain was, as anticipated, during the first few days. We made but little progress from the sixteenth to the twenty-third day, and also from the twenty-fourth to the thirtieth day. Of the six persons practicing addition, five of us also practiced the making of a maximum grip with a thumb and forefinger. Just before beginning the adding each day this maximum grip (or pinch) was exerted once a second for sixty seconds, first with the right hand and then with the left. Likewise at the completion of the addition sixty grips were taken by the right hand and sixty by the left. The total pressure exerted by each individual in the 240 trials (four minutes) was then recorded and expressed in kilograms. The result of the experiment is shown in curve B of Fig. 1. The average total pressure for each of the five persons was for the first day 620 kilograms; for the twenty-fourth day 1400 kilograms. Our increase was very rapid for the <p 226> first few days, and no general slump was encountered till the last week of practice. In one particular our results in the test on physical strength were not anticipated--we did not suppose that by practicing four minutes daily for thirty days we could double our physical strength in any such a series of maximum grips with the thumb and forefinger.