The Magnetic Orrery

Construct a round box, Fig. 16, about eight inches diameter, and half

an inch deep. On the bottom fix a circular pasteboard drawn like the

figure. You are likewise to have another pasteboard, drawn exactly the

same, which must turn freely in the box, by means of an axis placed on

a pivot, one end of which is to be fixed in the centre of the circle.



On each of the seven smaller circles on the pasteboard, which you have br />
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.






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 central circle to that question; and, putting one of the needles

on each of the seven circles, you turn it about, and when they all

settle, the seven words they point to compose the answer.



The moveable needle, whose point in the figure stands at September, is

to place against the names of the months; and when the party has fixed

upon a question, you place that needle against the month in which he

was born, which will make the ceremony appear a sort of magic

divination. The planetary signs are merely intended to aid this

deception, and give it the appearance of astrology.