5oo 



ENGINEERING ON THE FARM 



proper ignition. Where possible, battery connections should 

 be soldered to the ends of conductors so that the fastenings 



may be positive. Care 



Jhhonory e/ectroo'e 

 /nju/ateo' from p/uq 



Fig. 398. Wiring assembly as used on a 

 make-and-break ignition system 



should be taken to select 

 a conductor sufficiently 

 large to carry the current 

 with a minimum of re- 

 sistance. Any consider- 

 able resistance results in 

 a heating of the conduc- 

 tor. This is especially 



Contact 

 po/nte 



Jfar/o/?aru 

 e/ectroae 



/*7orab/e e/ec/rode 



f/ammer ' 

 fr/yyer 



important with storage batteries used for automobile starting. 

 The amperage pulled from a storage battery by an auto- 

 mobile starter may be as high as 350. This strength of 

 current calls for a 

 large wire, as may be 

 noted by an exami- 

 nation of a table of 

 carrying capacities. 



Magneto . The 

 magneto (Fig. 397, 

 page 505) is the sim- 

 plest form of electrical 

 generating machine. 

 Several types have 

 been used for ignition 

 purposes : the low- 

 tension, direct and 

 alternating current, 

 high-tension, and 

 inductor. When the 

 magneto is used on a 

 jump-spark system , 

 an outside breaker is 

 necessary. On a 

 multiple -cylinder 



Spring 



/Jammer 

 fr/yyer- 



Morab/e 

 e/ecfrode 



Fig. 399. 



5?af/onary 

 e/ec/rode 



/nsu/ab/on 



Cor>/acf 

 points 



make-and-break spark plu° 



