There is a lens inset in the scioptic ball opposite the telescope attachment; dia=3.0cm, f=21cm. Remove this lens and the screw-barrel microscope may be attached.
Scioptic Ball
Telescope attachment threads.
A scioptic ball is a mounting device for optical components. It consists of a wooden ball in a mounting frame. The ball can be oriented in any direction and then fixed in place with a retaining ring. The ball has a hole through the middle with brass mounts on either side where an optical microscope or telescope may be attached. The optical instrument faces into a darkened room. Loosening the retaining ring allows the ball to rotate freely, thus pointing the outside opening toward the sun. If a telescope is attached, the system would be used for visualizing sunspots or an eclipse. By removing the telescope and retaining ring, and turning the ball around, a screw-barrel microscope can be attached to visualize mounted specimens. Both the telescope and screw-barrel microscope were used to project images for audience viewing.
Screw-barrel microscope attached to the scioptic ball
Telescope attached to the scioptic ball.