, Jr., Huron, S. Dak.

** How to Make a Paper Phonograph Horn [71]

Secure a piece of tubing about 1-3/4 in. long that will fit the
connection to the reproducer, and wrap a quantity of heavy thread
around one end as shown in the enlarged sketch A, Fig. 1. Form a
cone of heavy paper, 9 in. long and 3 in. in diameter, at the
larger end with the smaller end to fit the diameter of the tube A,
making it three-ply thick and gluing the layers together. Attach
this cone on the tube A where the thread has been wrapped with
glue, as shown in Fig. 2. Fig. 2 is also an enlarged sketch. Make
ten pieces about 1 ft. 10 in. in length and 3 in. wide from the
thin boards of a biscuit or cracker box. Cut an arc of a circle in
them on a radius of 2 ft. (Fig. 3). Make a 10-sided stick, 12 in.
long, that will fit loosely in the tube A, to which nail the 10
pieces as shown in Fig. 4, connecting the bottom by cross pieces,
using care to keep them at equal distances apart and in a circle
whose diameter is about 2 ft.

[Illustration: Detail of Phonograph Horn]

The cone is placed over the stick as shown by the dotted lines in
Fig. 4 and temporarily fastened in position. Cut out paper
sections (Fig. 5) that will cover each space between the 10
pieces, allowing 1 in. on one side and the top, in which to cut
slits that will form pieces to overlap the next section and to
attach with glue. Fasten the sections all around in like manner.
The next course is put on in strips overlapping as shown at B,
Fig. 6. Finish by putting on sections in the same way as the first
course, making it three-ply thick. Remove the form, trim to suit
and glue a piece of paper over the edge. When the glue is
thoroughly hardened, put on two coats of white and one of blue
paint, shading it to suit and striping it with gold bronze.

** How to Make a Hygrometer [71]

A homemade hygrometer, for determining the degree of moisture in
the atmosphere, is shown in the accompanying sketch and consists
of a board, A, with a nail at each end to hold the silk thread B.
A second piece of silk thread, C, is tied to the center of B and
connects with an indicating hand or pointer supported by the
bracket D. The axle on which the pointer revolves consists of a
piece of round wood, about the size of a lead-pencil, with a pin
driven in each end. A piece of tin, E, is cut V-shaped at each end
and bent up at the ends to form bearings for the pins. The silk
thread C is fastened to