ivide
the ground glass into four equal parts.

Focus the camera in the usual manner, but get the picture desired
to fill only one of the parts on the ground glass. Place the
plate-holder in position and draw the regular slide; substitute
one of the slides prepared and expose in the usual way.

If a small picture is to be made in the lower left-hand corner of
the plate, place the prepared slide with the corner cut, as shown
in Fig. 1. The slide may be turned over for the upper left hand
corner and then changed for slide shown in Fig. 2 for the upper
and lower right-hand corners.

** Electric Blue-Light Experiment [47]

[Illustration: Electric Blue-light]

Take a jump-spark coil and connect it up with a battery and start
the vibrator. Then take one outlet wire, R, and connect to one
side of a 2-cp. electric lamp, and the other outlet wire, B, hold
in one hand, and press all fingers of the other hand on globe at
point A. A bright, blue light will come from the wires in the lamp
to the surface of the globe where the fingers touch. No shock will
be perceptible.

** Interesting Electrical Experiment [47]

The materials necessary for performing this experiment are:
Telephone receiver, transmitter, some wire and some carbons,
either the pencils for arc lamps, or ones taken from old dry
batteries will do.

Run a line from the inside of the house to the inside of some
other building and fasten it to one terminal of the receiver. To
the other terminal fasten another piece of wire and ground it on
the water faucet in the house. If there is no faucet in the house,
ground it with a large piece of zinc.

Fasten the other end to one terminal of the transmitter and from
the other terminal of the same run a wire into the ground. The
ground here should consist either of a large piece of carbon, or
several pieces bound tightly together.

[Illustration: A Unique Battery]

If a person speak into the transmitter, one at the receiver can
hear what is said, even though there are no batteries in the
circuit. It is a well known fact that two telephone receivers
connected up in this way will transmit words between two persons,
for the voice vibrating the diaphragm causes an inductive current
to flow and the other receiver copies these vibrations. But in
this experiment, a transmitter which induces no current is used.
Do the carbon and the zinc and the moist earth form a battery?
--Contributed by Wm. J. Slattery, Emsworth