细节
A lacquered-brass demonstration siren,
by Griffon & George Ltd.; a pair of discharge forks; a galvanometer by Nalder Bros & Co (ex-Wheatstone Laboratory No WL 13); an Elliott Bros resistance; a thermopile by Griffin London; a discharge plate, 8 7/8in. (22.7cm.) diam.; and a dip needle
See illustration (7)
by Griffon & George Ltd.; a pair of discharge forks; a galvanometer by Nalder Bros & Co (ex-Wheatstone Laboratory No WL 13); an Elliott Bros resistance; a thermopile by Griffin London; a discharge plate, 8 7/8in. (22.7cm.) diam.; and a dip needle
See illustration (7)