Jolly's Photometer Build to Order Bell-in-vacuum jar with a 4-6V

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

designed to hold visible iron-filing field lines and support side-by-side magnet-strength comparisons in mechanics labs

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

Solid glass friction rod that develops a positive electrostatic charge when rubbed with silk or wool

Jolly's Photometer Build to Order Bell-in-vacuum jar with a 4-6VBrightness comparing Jolly's photometer using a translucent paraffin disc method, the balanced position locating the photometric midpoint between two unequal light sources.