Put sides about 1-1/2 in. high around this apparatus, raising the
board a little from the bottom to allow room for the coil. A lid
may be added if desired. Connect up as shown.
--Contributed by Chas. H. Boyd, Philadelphia.



** How to Make a Simple Water Rheostat [43]

[Illustration: Wiring Plan for Water Rheostat]

The materials necessary are: One 5-point wood-base switch, 4 jars,
some sheet copper or brass for plates, about 5 ft. of
rubber-covered wire, and some No. 18 gauge wire for the wiring.

The size of the jars depends on the voltage. If you are going to
use a current of low tension, as from batteries, the jars need not
be very large, but if you intend to use the electric light current
of 110 voltage it will be necessary to use large jars or wooden
boxes made watertight, which will hold about 6 or 7 gal. Each jar
to be filled with 20 parts water to 1 part sulphuric acid. Jars
are set in a row in some convenient place out of the way.

Next cut out eight copper or brass disks, two for each jar. Their
size also depends on the voltage. The disks that are placed in the
lower part of the jars are connected with a rubber covered wire
extending a little above the top of the jar.

To wire the apparatus, refer to the sketch and you will see that
jar No. 1 is connected to point No. 1 on switch; No. 2, on No. 2,