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 



