Jolly's Photometer Build to Order Continuously motor-driven to supply a

Continuously motor-driven to supply a steady high-voltage source

Bell-in-vacuum jar with a 4-6V electric bell suspended on rubber cord inside a 22 by 15cm glass chamber

Four nesting aluminum pails on insulating feet

the larger working face giving longer beam paths for measurable lateral-displacement studies

letting students drive the lamp directly or send the slow AC output to a meter or oscilloscope

Jolly's Photometer Build to Order Continuously motor-driven to supply aBrightness comparing Jolly's photometer using a translucent paraffin disc method, the balanced position locating the photometric midpoint between two unequal light sources.