First line reads: 'When the finger-tip was drawn over a filled
distance of 2 cm., the subject _P_ measured off 3.8 on the
open surface, the subject _R_ 3.6, etc.' Each number is the
average of five judgments. In Table IX. the points were set at
regular intervals. In Table X. the filling was made irregular
by having some points rougher than the others and set at
different intervals.


I can give here only a very brief summary of the results with this
apparatus. In Tables IX. and X. I give a few of the figures which will
show the tendency of the experiments. In these tests a different
length and a different filling were given for each judgment. The
result of the experiments of this group is, first, that the _shorter
filled spaces are judged longer and the longer spaces shorter_ than
they really were. Second, that an increase in the number of points in
the filled space causes no perceptible change in the apparent length.
Third, that when the filling is so arranged as to produce a tactual
rhythm by changing the position or size of every third point, the
apparent length of the space is increased. It will be noticed, also,
that this is just the reverse of the result that was obtained for
passive touch. These facts, which were completely borne out by several
other experiments with different apparatus which I shall describe
later, furnish again a reason why different investigators have
hitherto reported the illusion to exist, now in one direction, now in
the other. Dresslar drew the conclusion from his experiments that the
filled spaces are always overestimated, but at the same time his
figures show an increasing tendency towards an underestimation of the
filled spaces as the distances increased in length. I shall later, in
connection with similar results from other experiments on this