Four Scientific Laboratory Apparatus, 19th/20th Century,
A Glass Piercer raised on glass insulating rods used in electrostatic demonstrations where a high-voltage electrostatic discharge (often from a Leyden jar) would pierce holes through insulating materials like thin glass or paper; a Leeds & Northrup Reflecting Galvanometer No. 26632 on a tripod base with leveling screws; a brass dual dial acoustic siren instrument based on Baron Charles Cagniard de la Tour's 1819 invention. It measures sound vibrations by forcing air through perforated rotating disks, allowing researchers to calculate pitch based on rotation speed;  and a disc-mounted microscope slide ringing table,
19th century, in mahogany and lacquered brass, used to prepare slides.

Largest Dimensions: H: 9 1/4 x W:7 7/8 x D: 3 3/8 in. General wear, scratches and grime commensurate with age and use. Interior mirror lens is spotted. #1 is written in black marker on back and bottom of dual dial instrument. Untested.