Crova's apparatus was designed for the purpose of representing vibratory movements on the screen, with 8 disks. Turning the crank past a vertical slit caused the disks to rotate, while a beam of light from the optical system impinged on the slit...
Electric discharges; Scientific apparatus and instruments
When connected to a power source, a bright electric spark would flash between the two ends of the two outer posts. The middle glass post is made of photo gray glass (yellow tinted glass), which would have glowed. This instrument is visible in early...
