Another Electric Orrery See Page 92
From the prime conductor of an electric machine suspend six concentric
hoops of metal at different distances from each other, in such a
manner as to represent in some measure the proportional distances of
the planets. Under these, and at a distance of about half an inch,
place a metallic plate, and upon this plate, within each of the hoops,
a glass bubble blown very thin and light. On electrifying the hoops,
the bubbles will be immediately attracted by them, and will continue
to move round the hoops as long as the electrification continues. If
the electricity be very strong, the bubbles will frequently be driven
off, run hither and thither on the plate, making a variety of
surprising motions round their axis; after which they will return to
the hoop, and circulate as before; and if the room be darkened, they
will all appear beautifully illuminated with electric light.