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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 76 



Gramme's Dynamo, 1871. 



These were commercially used, their main feature being the " ring 

 wound armature. 



Gramme's "Ring" Armature. 



Wire coils, surrounding an iron wire core, were all connected 

 together in an endless ring, each coil being tapped with a wire con- 

 nected to a commutator bar. 



