Drawing-board

Spider-web forks in envelope

Occultation reaction timer

Subminiature Foucault knife-edge tester

Radius measurer, plus older two-lamp radius gauge

Micro-monochromator

Horace Dall observatory

Early stereoview of Horace Dall

tin stereoviewer

Stereoscope plus stereo pictures

'totality' at a solar eclipse

See more related objects