Studies of instruments for measuring radiant energy in absolute value: An absolute thermobile
A 1916 technical paper from the National Bureau of Standards on instruments for measuring radiant energy in absolute value, written for physicists and instrument makers. The plates are line diagrams of a thermopile and its housing — sections, plan and rear views, dashed hidden edges, letter-keyed parts and dimension arrows in centimetres and millimetres, usable as apparatus schematics or measured-drawing motifs.
