le_ sense is in reality more often the stereognostic sense. That
is, they perceive by means of their hands the _form of bodies_.

It is the special muscular sensibility of the child from three to six
years of age who is forming his own muscular activity which stimulates
him to use the stereognostic sense. When the child spontaneously
blindfolds his eyes in order to recognize various objects, such as the
plane and solid insets, he is exercising this sense.

There are many exercises which he can do to enable him to recognize
with closed eyes objects of well defined shapes, as, for example, the
little bricks and cubes of Froebel, marbles, coins, beans, peas, etc.
From a selection of different objects mixed together he can pick out
those that are alike, and arrange them in separate heaps.

In the didactic material there are also geometrical solids--pale blue
in color--a sphere, a prism, a pyramid, a cone, a cylinder. The most
attractive way of teaching a child to recognize these forms is for him
to touch them with closed eyes and guess their names, the latter
learned in a way which I will describe later. After an exercise of
this kind the child when his eyes are open observes the forms with a
much more lively interest. Another way of interesting him in the solid
geometrical forms is to make them _move_. The sphere rolls in every
direction; the cylinder rolls in one direction only; the cone rolls
round itself; the prism and the pyramid, however, stand still, but the
prism falls over more easily than the pyramid.

* * * * *

[Illustration: FIG. 26.--SOUND BOXES.]

Little more remains of the didactic material for the education of the
senses. There is, however, a series of six cardboard cylinders, either
closed entirely or with wooden covers. (Fig. 26.)

When these cases are shaken they produce sounds varying in intensity
from loud to almost imperceptible sounds, according to the nature of
the objects inside the cylinder.

There is a double act of these, and the exercise consists, first, in
the recognition of sounds of equal intensity, arranging the cylinders
in pairs. The next exercise consists in the comparison of one sound
with another; that is, the child arranges the six cylinders in a
series according to the loudness of sound which they produce. The
exercise is analogous to that with the color spools, which also are
paired and then arranged in gradation. In this case also t