42 BELL SYSTEM TECHXICAL JOURX.IL 



insure good operation. Chatter can be largely eliminated b>- careful 

 mechanical design and the effect of the arc set up when the contact 

 is called upon tt) break the current in a circuit carrying se\eral watts 

 can be minimized somewhat by means of, so-called, spark killers. 

 These consist of condensers and resistances so proportioned as to 

 absorb the force of the arc in the charging of the condenser when the 

 contact opens. They can be utilized still further in niodif\ing the 

 shape of the transmitted wa\c' 1)\ tlie cliari;ing ol tlie condensiT wlien 

 the contact is opened. 



Telegraph relays and their applications have been referred to in this 

 paper only in the most general terms because of the variety of their 

 forms and uses. It is planned to cover this as well as other subjects 

 pertaining to rela\-s in a scries of later papers. 



