250 



Popular Science Monthly 



Push-buttons installed in the upper and lower halls and in 

 the bedrooms control the lamps, and the grounds can be 

 flooded with light when burglars or tramps are prowling 



Making a Bungalow Unpopular with 

 Night Prowlers 



THE evil-doer loves darkness rather than 

 light, so the Good Book says, and a 

 Toledo man has found in the saying a sug- 

 gestion for keeping tramps, burglars and 

 chicken thieves away from his residence. 

 The house is square and stands on a knoll, 

 so when he installed a powerful nitrogen 

 tungsten light in a reflector at each corner, 

 the whole place presented a brilliant 

 spectacle, not at all attractive to marauders. 

 The lights are controlled by push-buttons 

 inside the house. 



What a Circuit- Breaker 

 Really Is 



AN ordinary overload 

 xA. circuit-breaker is 

 merely an automatic electric 

 switch which is operated by 

 an electromagnet for opening 

 the circuit whenever the cur- 

 rent becomes dangerously 

 high. Circuit-breakers are 

 installed wherever large cur- 

 rents are employed, and if it 

 were not for them many 

 powerhouses would be burn- 

 ed up because of the tre- 

 mendous currents that would 

 develop from accidental 

 short circuiting. 



The accompanying illustra- 

 tion shows a type of circuit- 

 breaker that is now being 

 used extensively in manufac- 



turing plants. It can be ad- 

 justed to open a circuit at 

 a certain maximum current. 

 When such a point is reached, 

 the current flowing through a 

 copper coil will pull up the 

 plunger. This strikes against 

 the trigger and allows the 

 operating springs to pull out 

 the arm carrying the copper 

 and carbon contacts. The 

 carbons remain closed until 

 the copper bridge is lifted 

 from its contacts. The final 

 break in the circuit there- 

 fore is made by the carbons, 

 and hence the formation of 

 an arc on the copper is pre- 

 vented. This not only pre- 

 vents the copper bridge from 

 becoming fused, but it also 

 prevents the "copper from burning up. 

 There are numerous other types of 

 circuit-breakers serving many diff'erent 

 purposes. There are under-load breakers 

 for circuits that charge storage batteries, 

 which open the circuit should the charging 

 voltage drop and allow the batteries to dis- 

 charge into the charging source; and there 

 are others very much more elaborate in the, 

 powerhouses themselves. Such are the 

 distant-control breakers, for instance. 

 Should any serious trouble occur the con- 

 trol can be 

 operated and the 

 switch opened by 

 a push-button. 



In this cir- 

 cuit breaker 

 a copper 

 bridge is 

 made to rise 

 and open up 

 the carbon 

 contacts, the 

 final break 

 coming on 

 the carbons 



