Spectrometer converter

ABDNP:200602a

Wooden box with tube and lens form one end and "bellows" with a rectangular opening at the other. Turning wheel that opens and shuts aperture on side of box and handle to slide lens back and forth on tube with mm scale underneath marked every 5 mm from 0 to 20.
Used to convert a spectrometer to a spectrograph. Photosensitive paper would be placed over rectangular aperture and the lens, over the spectrometer eyepiece.

1800

length 530mm, width 190mm, lens diam.40mm

Wood, glass, metal (tube)

Unknown