Leipzig u. Wien, 1894, S. 128. Mach, Ernst, 'Beiträge zur
Analyse der Empfindungen,' Jena, 1900, S. 98.

These two cases in which the image is localized midway between _P_ and
_P'_ interest us no further. Localized on the final fixation-point,
the image is always felt to flash out suddenly _in situ_, just as in
the case of the 'correctly localized' after-image streaks in the
experiments with the perimeter. The image appears in one of four
shapes, Fig. 7: 2 or 3, 4 or 5.

First, the plain or elongated outline of the dumb-bell appears with
its handle on the final fixation-point (2 or 3). The image is plain
and undistorted if the eye moves at just the rate of the pendulum,
elongated if the eye moves more rapidly or more slowly. The point that
concerns us is that the image appears _with its handle_. Two
precautions must here be observed.

The eye does not perhaps move through its whole 42°, but stops instead
just when the exposure is complete, that is, stops on either _O_ or
_N_ and considerably short of _P_ or _P'_. It then follows that the
exposure is given at the _very last_ part of the movement, so that the
after-image of even the handle _h_ has not had time to subside. The
experiment is planned so that the after-image of _h_ shall totally
elapse during that part of the movement which occurs after the
exposure, that is, while the eye is completing its sweep of 42°, from
_O_ to _P_, or else from _N_ to _P'_. If the arc is curtailed at point
_O_ or _N_, the handle of the dumb-bell will of course appear. The
fact can always be ascertained by asking the subject to notice very
carefully where the image is localized. If the eye does in fact stop
short at _O_ or _N_, the image will be there localized, although the