whether the exercise has been
accurately performed; and by marking the time in any particular case,
the teacher can measure exactly, every week or month, the advance of
each pupil.

The mental advantages of this exercise are numerous. Among other things
it trains to a great command of the mind; and brings into exercise an
important principle formerly illustrated, (Part III. ch. xi. p. 288,) by
which the pupil acquires the ability to think one thing, and to do
another.

When the pupil is sufficiently expert at one line of figures, he should
be exercised upon the B side of the rod, containing the double line. He
is to practise adding each pair of the figures at a glance,--till he can
run them over without difficulty, as if they were single figures. He is
then to add a sum to _them_, as he did on the single line, till he can
add the sum and the double figure as readily as he did one. The C side
of the rod is to be treated in the same way;--first by adding all the
three figures at a glance, and naming the sum of each, till he can do it
as readily as if there was but one; and then he is to add any special
sum to them as before.

Note W, p. 321.--Children generally delight in music, and seldom weary
in its exercise. It forms therefore, when judiciously managed, a most
useful exercise in a school for the purposes of relaxation and variety,
and for invigorating their minds after a lengthened engagement in drier
studies. It thus not only becomes desirable to teach music in the
seminary as a branch of education for after life, but for the purposes
of present expediency.

That music may be taught to the young in a manner much more simple than
it has yet generally been done, is now matter of experience. The notes
are only _seven_, and these are each as precise and definite in
proportion to the key note as any letter in the alphabet. There is
obviously no difficulty in teaching a child seven figures,--and there is
in reality as little difficulty in teaching him seven notes; so that,
having the key note, he will, in reading a tune, sound each in its order
when presented to him, as readily and accurately as he would read so
many figures.

To render this exercise more simple to children, and more convenient in
a school, the notes have been represented by figures, 1 being the key
note. The other notes rise in the common gradation from 1 to 8, which is
the key note in alt. By this means, the teacher by writing on the common
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