de.

Secure a piece of 1-3/4-in. lead pipe, 5 in. long, and cut both
ends smooth and square with the pipe. Solder a circular disk of
lead to one end, forming a cup of the pipe. As this cup must hold
the sulphuric acid it must be perfectly liquid-tight. It is also
necessary to get another lead pipe of the same length but only
3/4-in. in diameter. In this pipe should be bored as many 1/8-in.
holes

[Illustration: Battery]

as possible, except for about 1 in. on each end. One end of this
tube is hammered together as shown at A in the sketch to make a
pocket to hold the paste. This, of course, does not need to be
watertight.

A box of wood is made to hold the larger tube or cup. This box can
be square, and the corners left open around the cup can be filled
with sawdust. A support is now made from a block of wood to hold
the tube, B, in place and to keep it from touching the cup C. This
support or block, D, is cut circular with the same diameter as the
lead cup C. The lower portion of the block is cut away so it will
just fit inside of the cup to form a stopper. The center of this
block is now bored to make a hole the same size as the smaller
lead pipe. Place the lead pipe in the hole and immerse it in
smoking hot paraffine wax, and leave it until the wood has become
thoroughly saturated with the hot wax. Use care to keep the wax
from running on the lead at any place other than the end within
the wood block. Two binding-posts should be attached, one to the
positive, or tube B, and the other to the negative, or tube C, by
soldering the joint.

A paste for the positive plate is made from 1 part sulphuric acid
and 1 part water with a sufficient amount of red lead added to
make of thick dry consistency. When mixing the acid and water, be
sure to add the acid to the water and not the water to the acid.
Also remember that sulphuric acid will destroy anything that it
comes in contact with and will make a painful burn if it touches
the hands. Stir the mixture with a stick and when a good dry paste
is formed, put it into the smaller tube and ram it down until the
tube is almost filled. The paste that may have come through the
holes is scraped off and the tube set aside to dry. The large tube
or cup is filled with a diluted solution of sulphuric acid. This
solution should be about one-twelfth acid. The cell is now
complete and ready for storing the current.

The cell may be charged with three gravity cells. These are
connec