Page:Popular Science Monthly Volume 88.djvu/147

 Popular Science Monthly

Connecting Block for Bell Wires

THIS connecting block is very handy for joining a number of wires from the same set of batteries, such as spark coils, door bells, light lamps, etc..

�� ���'To da/ fere/ —"^

As many bells as are wanted can

be attached to one set of batteries

by this simple connecting block

and as many wires as desired can be add- ed by simply adding more nuts on the bolts. A good idea of it can be ob- tained from the drawing.

The base can be made of hard wood such as oak or maple. It has four holes drilled in it. The two nearest the end are for No. 10 wood screws, to fasten it on the wall or table. The other two are for the brass bolts. The bottom of the base where the bolt heads rest, is drilled in about y^'' inch with a V-i!' drill. _

This is so the base to be level on the bottom when the bolts are inserted.

Ink Erasing Blotter

TAKE an ordinary sheet of blotting paper and steep it several times in a solution of oxalic aci4 or oxlate potas- sium and dry. While the ink spot is still moist apply the blotter and the ink will be extirely removed. If the ink is dry moisten and apply the blotter.

An Electric Alarm Clock

THE tall hall clock that is so frequent- ly found in the halls of old-fashioned houses can be readily converted into a very serviceable and eftective electric alarm clock without in any way impair- ing the dignity of its appearance. The face of the clock, if mounted on metal, should, as the first step, be removed from the metal and remounted on a wooden back, so as to provide proper insulation. Bore y^' holes beside each of the figures

��iig

as shown in the sketch. Each of these holes should receive a copper rivet long enough to extend i/i6" above the face of the clock. Soldered to the back of each rivet is a copper wire of the kind used in bell wiring. By means of 12 such wires, the rivets in the face of the clock are connected to the contact points on a i2-point switch, which is numbered to correspond to the figures on the dial. A dry battery, concealed in the base of the clock, is connected with the works at one terminal, and to the bell and switch at the other pole. Now solder to the small hand a very fine spring wire so that it will come in contact with the cop- per rivets beside the numbers. To set the alarm, for example, at 6 o'clock, turn the switch handle to the number 6. When the hour hand comes in contact with 6 on the dial, the bell will ring until the switch is turned off, or until the hand has moved away from the contact. By using a pleasant bell, harsh sound- ing effects may be eliminated.

���Oroundon

��How to make a grandfather clock into an efficient alarm clock with- out changing its outward aspect

�� �