Signalman n. (pl. signalmen) A man whose business is to manage or display signals; especially, one employed in setting the signals by which railroad trains are run or warned.
... askaris; the hill's black with them!' So the signalman cried to the doctor, as he sped by on a message. I was interested in watching the gun-layer as he readjusted the dragon mouth. But what had my friend of the sand-bags to do with the matter? He moved ... — Cinderella in the South - Twenty-Five South African Tales • Arthur Shearly Cripps