Connect the tops with a wire, from the centre of which hangs a brass ball to a raw-silk thread, to come in contact with a bell on the base of each column when reared upright upon a stand. One column has its positive end opposed to the other’s negative one, which makes the two, when connected above, one continuous column. Groove the stand, and cover all with a glass shade oval or round.
The ball will swing to and fro between the bells, repelled and attracted alternately.
To recover lost power, insulate the columns for a few days.
SIMPLE ELECTROSCOPE.
Drive the eye of a needle into a cork and stop a bottle with it, the point being up. At the balancing-spot of an eagle’s feather glue a little hard socket or cup of glass or metal, and place it on the needle point.
Sealing wax, a vulcanite comb passed rapidly through the hair, or other “excited” electrifier, will cause the feather to whirl round and follow it as iron will the magnet.
THE OBEDIENT BROWNIE.
Hang a penny between the poles of an electro-magnet, and spin it round. On making the connection with the battery, the coin will be stopped short, and will place itself in the equatorial position.