, Pa.

** A Cheap Fire Alarm [47]

An electrical device for the barn that will give an alarm in case
of fire is shown in the accompanying diagram. A is a wooden block,
which is fastened under the loft at a gable end of the barn; B is
an iron weight attached to the string C, and this string passes up
through the barn to the roof, then over a hook or pulley and
across the barn, under the gable, and is fastened to the opposite
end of the barn.

D D are binding posts for electric wires. They have screw ends, as
shown, by which means they are fastened to the wooden block A.
They also hold the brass piece E and the strip of spring brass F
in place against the wooden block. G is a leather strap fastened
to the weight B and the spring F connected to the latter by a
small sink bolt.

[Illustration: Electric Fire Alarm]

At the house an electric bell is placed wherever convenient.
Several battery cells, of course, are also needed. Dry batteries
are most convenient. The battery cells and bell are connected in
the usual manner, and one wire from the bell and one from the
battery are strung to the barn and connected to the binding posts
D D.

If a fire occurs in the hay-mow the blaze will generally shoot
toward the gable soon after it starts, and will then burn the
string C, which allows the weight B to fall and pull the brass
spring against the iron piece E, which closes the circuit and
rings the bell in the house.

If desired, the string may be stretched back and forth under the
roof several times or drawn through any place that is in danger of
fire.
--Contributed by Geo. B. Wrenn, Ashland, Ohio.

** How to Make a Small Electric Furnace [48]

Take a block of wood and shape into a core. One like a loaf of
bread, and about that size, serves admirably. Wrap a layer of
asbestos around it and cover this with a thin layer of
plaster-of-paris. When the plaster is nearly dry wind a coil of
No. 36 wire around it, taking care that the wire does not touch
itself anywhere. Put another course of plaster-of-paris on this,
and again wind the wire around it. Continue the process of
alternate layers of plaster and wire until 500 ft. or more of the
latter has been used, leaving about 10 in. at each end for
terminals. Then set the whole core away to dry.

For a base use a pine board 10 in. by 12 in. by 1 in. Bore four
holes at one end for binding-posts, as indicated by E E. Connect
the holes in pairs by ordinary house fuse w