Page:Popular Science Monthly Volume 88.djvu/659

 Popular Science Monthly

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��A Burglar-Alarm for the Unprotected Chicken-House

CHICKEN-FANCIERS and poultry- farmers will be interested in an electric alarm which is set ringing by thieves. The favorite means of entrance, provided the door is securely locked, is through the windows of the coop. The installation of the usual type of burglar- alarm involves an outlay for costly equip-

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��When the chicken thief breaks the thin

wires covering the window, he opens the cir-

cvdt, the buzzer-armature drops, and the

alarm bell rings

ment. The apparatus to be described is inexpensive, and may be easily installed.

A row of wire nails about 1'" apart should be driven into the window-frame above and below. Fine cotton-insulated, magnet-wire should be strung up and down over the two rovv^s of nails, as shown in the diagram. The two ends should be led to a gravity cell, and also to the magnets of a buzzer. The arma- ture of the buzzer should be disconnect- ed, but not removed, as it will have an- other use. By consulting the diagram of connection it will be obvious that if the wires over the window are intact, the armature will be drawn down upon the magnet-cores, away from the contact. Wires connected with a bell and dry bat- teries in the house — the distance makes no difference — should be brought to the armature of the buzzer and to the con- tact that touches it.

The operation is as follows : When a marauder attempts to enter the window, he breaks the wires — which he assumes to be strings — with a sweep of the hand. The circuit, suddenly opened, allows the armature of the buzzer to fall back against the contact. This closes the bell

��circuit and causes the bell to ring in the house. If there are several windows in the chicken-barn, the wires covering all of them should be connected in series. Gravity or blue vitriol batteries should be used for the magnet circuit.

How to Shingle Without Leaving Nail-Holes

THE illustration will show how a 1' by 6' straightedge, or longer, can be used to lay shingles 2>/-^' by 8" or 2" by 7", according to the weather, on the side of a building, without nailing the straightedge on to the shingles and thus leaving unsightly holes. Any blacksmith will make four hooks out of V2'' by %" iron and twist them so that the shank can be screwed on the ends of the straightedge, and so that the hook part will extend down and under the last course of shingles, as indicated in Fig. 2. The iron is drawn out to 1/16'' thick- ness, and the spurs on the hook part are made by cutting a V in the hook while it is hot and turning it back and filing it down to a sharp edge. This spur holds the straightedge in place. It is well to have this part of the hook offset clear of the ends of the straightedge (Fig. 1). x\fter the straightedge is in place, a slight tap of a hammer over the shingle will drive the spur into the shingle under- neath. No holes will be left to mar the face of the work. A slight jerk will pull the spur out and the straightedge is then ready to be used for the next course.

���Details of a shingling device which keeps the edges straight without driving nail- holes into the exposed ends

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