In the amphibrachic form the changes manifested by the constituents of the unit group are more obscure.  No progressive retardation of the accented element is apparent.  In the initial and final intervals the difference in duration between the first and last members of the series is small and appears early in the process.  If we assume the general application of the laws of change presented in the preceding section, there should be here two influences concerned in the determination of the relations presented, the factors, namely, of position and accent.  The falling of the accentual stress on the median interval eliminates one of the two factors of progressive reduction in that element and replaces it by a factor of increase, thereby doing away with the curve of change; while at the same time it decreases the changes which occur in the bounding intervals of the group by removing the accent from the first and by the proximate position of its own accent tending to reduce the last interval.

Under this same assumption there should be expected in the anapaestic form of rhythm an exaggeration of the progressive increase in the final interval, together with a further reduction in the duration of the initial; since from the falling of the accent on the final interval two factors of increase combine, while in the initial, which immediately follows the accented interval in the series, a positive factor of reduction appears.  This is actually the type of change presented by the quantitative relations, which are given as proportional values in the following table.

TABLE XLI.

  Interval.  I II III IV V VI VII VIII IX X
  First, 1.000 0.950 1.000 0.950 1.000 0.950 1.000 1.000 1.000 1.050
  Second, 1.000 1.100 1.000 1.050 1.100 1.000 1.000 1.050 1.100 1.000
  Third, 1.000 1.073 1.073 1.024 1.024 1.122 1.098 1.098 1.098 1.146

Between its first and last terms the first interval shows a departure slightly less than that of the previous rhythm from the rate of change which characterizes the dactylic type; but if the average values of the whole series of intervals be taken in each of the three cases, the progressive reduction will be seen clearly to continue in passing from the second to the third form.  The figures annexed give these averages as proportions of the first interval in the series.

TABLE XLII.

1st      Av. of
Rhythm.          Interv.   all others. 
Dactylic,        1.000  :   1.188
Amphibrachic,    1.000  :   1.019
Anapaestic,       1.000  :   1.000

The relations of the various intervals in the three forms are put together here for comparison: 

TABLE XLIII.