ich is to be fixed in the centre of the circle.

On each of the seven smaller circles on the pasteboard, which you have
fixed at the bottom of the box, place a magnetic bar, two inches long,
in the same direction with the diameters of those circles, and their
poles, in the situations expressed in the figure.

There must be an index like the hour hand of a dial, fixed on the axis
of the central circle, by which the pasteboard circle in the box may
be turned about; also a needle (forming in the figure the other hand)
that will turn freely on the axis, without moving the circular
pasteboard.

In each of the places where the word _question_ is, write a different
question; and in each of the seven circles where the planetary signs
are, write two answers to each question; observing, that there must
only be seven words in each question: for instance,

In division No. 1, of the circle G, which stands opposite question
No. 1, write the first word of the first answer. In the division No.
2, of the next circle, write the second word; and so on to the last,
which will be in the seventh division of the seventh circle.

[Illustration: Fig. 16.]

In the eighth division of the first circle, write the first word of
the second answer; in the ninth, the second word of the same answer;
and so on to the fourteenth division of the seventh circle, which must
contain the last word of that answer.

The same must be done for all the seven questions, and to each of
these must be assigned two answers, the words of which are to be
dispersed through the seven circles.

At the centre of each of these circles place a pivot, and have two
sets of magnetic needles like the hands of a watch, the pointed end of
one set being north, and the other south.

Now, the index of the central circle being directed to any one of the
questions, if you place one of the two magnetic needles on each of the
seven lesser circles, they will fix themselves according to the
directions of the bars on the corresponding circles at the bottom of
the box, and consequently point to the seven words that compose the
answer. If you place one of the other needles on each circle, it will
point to the words that are diametrically opposite to those of the
first answer, the north pole being in the place of the south pole of
the other.

You therefore present this orrery to any person, and desire him to
choose one of the questions there written. You then set the index of
the cen