Copy of Amperes commutator
1877
Ruhmkorff commutator
1872
Bertin commutator
1886
Thomson commutator motor meter
Clarke's commutator
1836-1851
Double tongue commutator used by Wheatstone
1861
Smith's mercurial commutator
1902
Ruhmkorff commutator
Pohl commutator
1872
Pohl commutator
1872
Battery commutator for Siemens Universal galvanometer
1873-1890
Ruhmkorff commutator
Double wheel commutator
Line commutator with 12 plugs (G N T Model 758)
Two Pohl commutators (see 2 stroke nos).
1872
Commutator, Pohl type
1920-1943
Hand commutator
1879
BTM/Hollerith Upper Counter Commutator, c.1939
1939
Circular commutator
Bertin commutator by Townson and Mercer
1897-1918