Here again there is no progressive acceleration or retardation. The rhythmical differentiation of alternate measures is very slight—the average ratio of the first to the second being 1.000:0.993—but is of the same type as in the preceding. The excess in the amount of this differentiation presented by the first type of reaction over the second may be due to the presence of a tendency to impart rhythmical character to such a series of reactions, which, prohibited in one form—the intensive accent—finds expression through the substitution for this of a temporal form of differentiation.
In this trochaic rhythm the phases of variation in the constituent intervals of the measure are concomitant, and their indices of differentiation almost identical with each other. Their values are, for the first, 1.000:0.979; and for the second, 1.000:0.995. The higher index is that of the first interval, that, namely, which follows the accented beat of the measure, and indicates that the rhythmical change is due chiefly to a differentiation in the element which receives the stress.
In iambic measures similarly beaten out there is likewise no acceleration nor retardation apparent in the progress of the tapping. The temporal differentiation of alternate measures is of the same extent as in the preceding group, namely, 1.000:0.991. the proportional quantitative values of the measure and its constituent intervals, taken in series of ten successive repetitions, are as follow:
TABLE XXXVII.
| Quantity. | I | II | III | IV | V | VI | VII | VIII | IX | X |
|---|---|---|---|---|---|---|---|---|---|---|
| Measure, | 1.000 | 0.979 | 1.000 | 0.979 | 1.020 | 0.979 | 0.979 | 1.020 | 0.979 | 0.979 |
| 1st Int., | 1.000 | 0.941 | 0.941 | 1.000 | 1.000 | 0.941 | 8.082 | 0.941 | 0.941 | 0.941 |
| 2d Int., | 1.000 | 1.000 | 1.032 | 0.967 | 1.032 | 1.000 | 1.000 | 1.032 | 1.000 | 0.967 |
The alternation of greater and less duration in the rhythm groups is due to a variation in the time-value of the second interval only, the index of average change in the first member being zero. That is, the greater index of instability again attaches to that element which receives the stress. Though this holds true throughout these experiments, the amount of difference here is misleading, since on account of the smaller absolute value of the first interval the proportional amount of change within it which passes unrecorded is greater than in the case of the second interval.
In general, the larger temporal variations of the trochaic and iambic rhythm forms are too slight to be significant when taken individually. The evidence of rhythmical treatment in such a series of reactions, which is strongly marked in the unaccented form, nevertheless receives reinforcement from these inconsiderable but harmonious results.
The proportional values of the variations in alternate measures for accented and unaccented elements are given in the following table, in which the figures for the trochaic and iambic forms are combined:
TABLE XXXVIII.
| Interval. | I | II | III | IV | V | VI | VII | VIII | IX | X |
|---|---|---|---|---|---|---|---|---|---|---|
| Accented, | 1.000 | 1.000 | 1.083 | 1.000 | 1.041 | 1.000 | 1.083 | 1.000 | 1.041 | 1.000 |
| Unacc. | 1.000 | 1.000 | 1.000 | 1.035 | 1.071 | 1.000 | 0.964 | 1.000 | 1.000 | 1.000 |