A number of people have asked how I made the Leyden jar array used with the "Tabletop Tesla Coil." In this separate Instructable I offer a detailed explanation of how the battery was made and what it can do.
Historical footnote: Ben Franklin created the term "Leyden battery" to describe grouping a number of Leyden jars together. He made the analogy to a battery of cannons. More cannons=more boom, more Leyden jars=more zap.
Leyden jars are the oldest form of capacitor. Basically they capture and store electricity, releasing it for use by other components in he circuit. The Leyden jar was invented in 1744-45 by two men, working independently: Ewald von Kleist and Pieter van Musschenbroek. Their original version used a glass jar filled with water. Basically a capacitor consists of two conductive surfaces separated by a dielectric (an insulator). The early Leyden jar was a glass jar filled with a saline or acid solution. A metal terminal passed through the top of the jar into the water; the outside of the jar was coated with metal foil.
In 1899, Nikola Tesla used banks of liquid-filled mineral water jars as the capacitor array for his high voltage radio and power transmission experiments in Colorado Springs. Modern Tesla coil builders often use homemade capacitors in their projects, usually made from beer bottles, aluminum foil, and salt water. There are other kinds of homemade capacitors--glass plates sandwiched with layers of foil, rolled sheets of polyethylene and foil, etc. The trend among coilers seems to be away from homemade capacitors and using instead "MMCs," or Multiple-Mini-Capacitors. These are arrays of high voltage commercial capacitors arranged in series and parallel to give the desired capacitance and voltage rating. Problem is, high voltage capacitors can be expensive and hard to find. When you do find high voltage caps, they may not be suitable for Tesla coil use, as the high frequency pulsations of power through a Tesla circuit impose severe stress on the components.
Because I'm cheap and have a long standing interest in old-fashioned technology, I decided to develop a dry, non-liquid Leyden jar that would work with a Tesla coil. I wanted a capacitor made of easily obtained materials that was sturdy, effective, and cheap. What follows is the design I've come up with so far.