|Builder:||Mather & Platt, Siemens, C&SL Stockwell Works,
Crompton & Company, Electric Construction Company, Thames Ironworks
|Engine:||2 Edison-Hopkinson traction motors (500v DC third rail)|
|Power:||100 hp (75 kW)|
The C&SLR tunnel had a very limited diameter of just over three metres with a rolling stock gauge just over two metres wide. The C&SLR Locomotives were only three metres long. The locomotives has two electric motors controlled by a hand-operated rotary controller. The controller was originally mounted vertically with exposed electrical contacts but later a horizontal enclosed controller similar to those used on electric trams was used.
The C&SLR locomotives hauled trains of three passenger coaches. At each terminus the locomotive would be uncoupled and another locomotive following behind would be coupled to the other end to take the train back. The tiny locomotives struggled with fully loaded trains especially with the steep gradients and twisty tunnels at King William Street. Sometimes the locomotive would not make it and the driver had to back the train back down to the level part of the tunnel (under the Thames) and make another attempt!  When the C&SLR extended Northwards to Moorgate King William Street as closed in 1900, earning it the dubious honour of being the first tube station to close. Without the restrictions of King William Street the C&SLR could operate longer trains.
Later locomotives had four-pole motors, built-in air compressors (the earlier locomotives filled a reservoir at Stockwell for their brakes) and nose-suspended motors though the limited tunnel dimensions meant the external appearance of the locomotives did not change much. The C&SLR was closed for reconstruction in the early 1920s, the tunnels being widened to match other (and later) tube lines. This now allowed the C&SLR line (which became part of the Northern Line) to use Standard Stock. The C&SLR locomotives were withdrawn by 1925. One has been preserved.
|Preserved C&SLR Locomotive #13 at London Transport Museum|
|Inside the cab of the preserved locomotive|
|C&SLR Locomotive and it's train, public domain image |
|Drawing of C&SLR train, public domain image |
 Piers Connor, The London Underground Electric Train (Crowood Press, 2015) p.10
 "City & South London", The Street Railway Review Vol. 3 (1893) p. 590
 "London's Subterranean Electric Railway", The Electric Railway Gazette No.12 (December 1890) p. 231
 J.E. Connor, London's Disused Underground Stations (Capital Transport, 2012) p. 9