Letter from [William George] Armstrong, Cragside, Rothbury, to [Alan Archibald Campbell] Swinton, 66 Victoria [Street], London, S.W He has returned to the tracings of the contact breakers which he believes are neatly and compactly arranged. Informs he approves of the plug switch on each circuit and prefers it to the commutator arrangement but questions the placement of such heavy a head on each vibration, elaborating on his thoughts. Mentions he will be in London the following month and hopes that Mr [Alfred] Apps will have everything completed by then. 11 February 1891