THE TRANSFORMER. 199 



fine wire (high voltage) coils being wound over the coarse wire 

 (low voltage) coils. The core, Fig. 164, is built up of rectangu- 

 lar strips of sheet iron which interleave with each other at the 

 corners c c c c. 



The shell-type transformer. A transformer in which the coils 

 form an elongated structure shaped like Fig. 164, and are sur- 

 rounded by laminated iron, is called a shell-type transformer. 



Finished coi's. 

 Fig. 169. 



Figure 165 shows the assembled windings of a small shell- type 

 transformer of the Allis-Chalmers Company, and Fig. 166 shows 

 the coils surrounded by the laminations. 



A somewhat clearer idea of the structure of the shell-type 

 transformer may be obtained from Figs. 167, 1 68, 169 and I/O, 

 which represent a large shell-type transformer of the General 

 Electric Company. Figure 167 shows one of the flat sections 

 of the windings in the process of construction ; two such coils 



