ted in series and the positive terminal binding-post on the
storage cell is connected to the wire leading from the copper
plate in the gravity cell. The other plate is connected to the
zinc. The first charge should be run into the cell for about one
week and all subsequent charges should only take from 10 to 12
hours.

** Fitting a Plug in Different Shaped Holes [122]

A certain king offered to give the prince his liberty if he could
whittle a plug that would fit four different shaped holes, namely:
a square hole, a round one, an oblong one and a triangular one,
says the Pathfinder. A broomstick was used to make the plug and it
was whittled in the shape shown

[Illustration: Fits Four Different Shaped Holes]

in Fig. 1. The holes in the different places as shown in Fig. 2,
were fitted by this one plug.

** How to Make a Lightning Arrester [122]

Secure a piece of wood about 3-1/2 in. square that will furnish a
nice finish and round the corners and make a small rounding edge
as shown in the sketch. From a piece of brass 1/16 in. thick cut
two pieces alike, A and B, and match them together, leaving about
1/16 in. between their upper edges and fasten them to the wood
with binding-posts. The third piece of brass, C, is fitted

[Illustration: Lightning Arrester]

between the pieces A and B allowing a space of 1/16-in. all around
the edge. One binding-post and a small screw will hold the piece
of brass, C, in place on the wood. The connections are made from
the line wires to the two upper binding-posts and parallel from
the lower binding-posts to the instrument. The third binding-post
on C is connected to the ground wire. Any heavy charge from
lightning will jump the saw teeth part of the brass and is
grounded without doing harm to the instruments used. --Contributed
by Edwin Walker, Chicago, Ill.

** A Home-Made Punt [123]

A flat bottom boat is easy to make and is one of the safest boats,
as it is not readily overturned. It has the advantage of being
rowed from either end, and has plenty of good seating capacity.

This punt, as shown in Fig. 1, is built 15 ft. long, about 20 in.
deep and 4 ft. wide. The ends are cut sloping for about 20 in.
back and under. The sides are each made up from boards held
together with battens on the inside of the boat near the ends and
in the middle. One wide board should be used for the bottom piece.
Two pins are driven in the top board of each side to serve as
oarlo