The Standard Electrical Dictionary

1. Tube, Electric

   A tube of glass around which is pasted a series of tinfoil circles, diamonds, or little squares, or other form of interrupted conductor. The pieces generally are placed in the line of a spiral. When a static discharge of electricity takes place along the conductor a row of bright sparks is produced at the breaks in the conductor. These by reflection are multiplied apparently, and a beautiful effect of intersecting or crossing spirals of sparks is presented. The experiment is in line with the luminous pane and lightning jar, and is used merely as a demonstration, or lecture experiment. Synonym--Luminous Tube.