e materials necessary for the T-shaped
boomerang are: One piece of hard maple 5/16 in. thick, 2-1/2 in.
wide, and 3 ft. long; five 1/2-in. flat-headed screws. Cut the
piece of hard maple into two pieces, one 11-1/2 in. and the other
18 in. long. The corners are cut from these pieces as shown in
Fig. 2, taking care to cut exactly the same amount from each
corner. Bevel both sides of the pieces, making the edges very thin
so they will cut the air better. Find the exact center of the long
piece and make a line 1-1/4 in. on each side of the center and
fasten the short length between the lines with the screws as shown
in Fig. 3. The short piece should be fastened perfectly square and
at right angles to the long one.

The materials necessary for the cross-shaped boomerang are one
piece hard maple 5/16 in. thick, 2 in. wide and 30 in. long and
five 1/2-in. flat headed screws. Cut the maple- into two 14-in.
pieces and plane the edges of these pieces so the ends will be
1-1/2 in. wide, as shown in Fig. 4. Bevel these pieces the same as
the ones for the T-shaped boomerang. The two pieces are fastened
together as shown in Fig. 5. All of the boomerangs when completed
should be given several coats of linseed oil and thoroughly dried.
This will keep the wood from absorbing water and becoming heavy.
The last two boomerangs are thrown in a similar way to the first
one, except that one of the pieces is grasped in the hand and the
throw given with a quick underhand motion. A little practice is
all that is necessary for one to become skillful in throwing them.
--Contributed by O. E. Tronnes, Wilmette, Ill.

** How to Make Water Wings [202]

Purchase a piece of unbleached muslin, 1 yd. square. Take this and
fold it over once, forming a double piece 1-1/2 ft. wide and 3 ft.
long. Make a double stitch all around the edge, leaving a small
opening at one corner. Insert a piece of tape at this corner to be
used for tying around the opening when the bag is blown up. The
bag is then turned inside out, soaked with water and blown up. An
occasional wetting all over will prevent it from leaking. As these
wings are very large they will prevent the swimmer from sinking.
--Contributed by W. C. Bliss, St. Louis, Mo.

** How to Make an Ammeter [203]

The outside case of this instrument is made of wood taken from old
cigar boxes with the exception of the back. If carefully and
neatly made, the finished instrument will be very satisfactory.