s thus able to see at a glance how nearly the results of the
different sittings correspond.

His results, put very briefly, fail to confirm the theory that the
sense of temperature has an apparatus of fixed spots for heat and
other fixed spots for cold. For when he puts the different markings
for heat together he finds that the spots are not the same, but that
those of one frame fall between those of another, and if several are
put together the points fill up a greater or smaller area. The same
for the cold spots; they fill a continuous area. He finds, however, as
other investigators have found, that the heat areas are generally in
large measure separate from the cold areas, only to a certain extent
overlapping here and there, and also that there are regions of the
skin where we have very little sense of either sort of temperature.

The general results will show, therefore, if they should be confirmed
by other investigators, that our temperature sense is located in what
might be called somewhat large blotches on the skin, and not in minute
spots; while the evidence still remains good, however, to show that we
have two senses for temperature, one for cold and the other for hot.

II. _Reaction-Time Experiments._--Work in so-called "reaction times"
constitutes one of the most important and well-developed chapters in
experimental psychology. In brief, the experiment involved is this:
To find how long it takes a person to receive a sense impression of
any kind--for example, to hear a sound-signal--and to move his hand or
other member in response to the impression. A simple arrangement is as
follows: Sit the subject comfortably, tap a bell in such a way that
the tapping also makes an electric current and starts a clock, and
instruct the subject to press a button with his finger as soon as
possible after he hears the bell. The pressing of the button by him
breaks the current and stops the clock. The dial of the clock
indicates the actual time which has elapsed between the bell (signal)
and his response with his finger (reaction). The clock used for exact
work is likely to be the Hipp chronoscope, which gives on its dials
indications of time intervals in thousandths of a second. For the sake
of keeping the conditions constant and preventing disturbance, the
wires are made long, so that the clock and the experimenter may be in
one room, while the bell, the punch key, and the subject are in
another, with the door closed. This m