The Campbell Gas Engine Company, Halifax

This afternoon I came across this interesting feature, neatly built in to a drystone wall. 

The company was established in 1883 by Hugh Campbell. He was born in Scotland and did an apprenticeship at Dunsmuir and Jackson, Govan and became a mechanical engineer. He invented and designed gas engines, suction gas plants and was the first to invent and produce the cold-starting crude oil engine.