 Bald was a cousin of William Bald (1789–1857) the civil engineer and cartographer, and acted as sponsor for William's membership of the Royal Society in 1829.Bald had enormously broad range of interests, visible in the large number of learned societies he was a member of and in the subjects on which he wrote.These range from articles and letters on mining engineering, palaeontology and archaeology, marine steam propulsion and metallurgy.