ML-ZW X-ray tube by Machlett. England, 1938-1955 ML-ZW X-ray tube by Machlett. England, 1938-1955 1938-1955
Electrically illuminated liquid prismatic compass by Kelvin, Bottomley and Baird, early 20th century Surveying compass, British, 1913-1920 1913-1920
Photograph of Amsler current meter by Stanley, 1915 Photograph of Amsler current meter by Stanley 1915
Brunton pocket transit compass with case by E.R. Watts, c.1930 Brunton pocket transit compass with case, 1925-1930 1925-1930