_ to _c_, the ends of which wire
are bent at right angles and run into the board. The plate will
consequently turn on this axis, as on a hinge. At the top of the plate
_d_, a small projection of the tin turns inwards, and to this, one end
of the cord _m m_ is attached. This cord passes back from _d_ to _a_
small pulley at the upper part of the board, and at the tower end of it
a tassel, loaded so as to be an exact counterpoise to the card, is
attached. By raising the tassel, the plate will of course fall over
forward till it is stopped by the part _b_ striking the board, when it
will be in a horizontal position. On the other hand, by pulling down the
tassel, the plate will be raised and drawn upwards against the board, so
as to present its convex surface, with the words STUDY HOURS upon it,
distinctly to the school. In the drawing it is represented in an
inclined position, being not quite drawn up, that the parts might more
easily be seen. At _d_, there is a small projection of the tin upwards,
which touches the clapper of the bell suspended above, every time the
plate passes up or down, and thus give notice of its motions.

[Illustration]

Of course the construction may be varied very much, and it may be more
or less expensive, according to the wishes of the teacher. In the first
apparatus of this kind which I used, the plate was simply a card of
pasteboard, from which the machine took its name. This was cut out with
a penknife, and after being covered with marble paper, a strip of white
paper was pasted along the middle, with the inscription upon it. The
wire _c c_ and a similar one at the top of the plate, were passed
through a perforation in the pasteboard, and then passed into the
board. Instead of a pulley, the cord, which was a piece of twine, was
passed through a little staple made of wire and driven into the board.
The whole was made in one or two recesses in school, with such tools and
materials as I could then command. The bell was a common table bell,
with a wire passing through the handle. The whole was attached to such a
piece of pine board as I could get on the occasion. This coarse
contrivance was, for more than a year, the grand regulator of all the
movements of the school.

I afterwards had one made in a better manner. The plate is of tin,
gilded, the border and the letters of the inscription being black. A
parlor bell rope passes over a brass pulley, and then runs downward in a
groove made in the m