may be located in any convenient place and wires run to that point.

[Illustration: _Fig. 55._ ALARM SWITCH ON WINDOW]

[Illustration: _Fig. 56._ BURGLAR ALARM ATTACHMENT TO WINDOW]

BURGLAR ALARM.--In order to make a burglar alarm connection with a bell,
push buttons or switches may be put in circuit to connect with the
windows and doors, and by means of the annunciators you may locate the
door or window which has been opened. The simplest form of switch for a
window is shown in the following figures:

The base piece (A), which may be of hard rubber or fiber, is 1/4 inch
thick and 1" x 1-1/2" in size.

[Illustration: _Fig. 57._ BURGLAR ALARM CONTACT]

At one end is a brass plate (B), with a hole for a wood screw (C), this
screw being designed to pass through the plate and also into the
window-frame, so as to serve as a means of attaching one of the wires
thereto. The inner end of the plate has a hole for a round-headed screw
(C') that also goes through the base and into the window-frame. It also
passes through the lower end of the heart-shaped metal switch-piece
(D).

The upper end of the base has a brass plate (E), also secured to the
base and window by a screw (F) at its upper end. The heart-shaped switch
is of such length and width at its upper end that when it is swung to
the right with one of the lobes projecting past the edge of the
window-frame, the other lobe will be out of contact with the plate (E).

[Illustration: _Fig. 58._ NEUTRAL POSITION OF CONTACT]

The window sash (G) has a removable pin (H), which, when the sash moves
upwardly, is in the path of the lobe of the heart-shaped switch, as
shown in Fig. 56, and in this manner the pin (H) moves the upper end of
the switch (D) inwardly, so that the other lobe contacts with the plate
(E), and establishes an electric circuit, as shown in Fig. 57. During
the daytime the pin (H) may be removed, and in order to protect the
switch the heart-shaped piece (D) is swung inwardly, as shown in Fig.
58, so that neither of the lobes is in contact with the plate (E).

WIRE CIRCUITING.--For the purpose of understanding fully the circuiting,
diagrams will be shown of the simple electric bell with two push
buttons; next in order, the circuiting with an annunciator and then the
circuiting necessary for a series of windows and doors, with annunciator
attachments.

[Illustration: _Fig. 59._ CIRCUITING FOR ELECTRIC BELL]

CIRCUITING SYSTEM WITH A BELL AND TWO PUSH B