Interesting listing for early Leyden Jar spark transmitter capacitors (not mine ... no benefit to me if you buy em):

eBay item number:193898727053

Copy of an original period catalog page indicates the capacitance in terms of jar volume (1 1/2 pints) and zapping power when charged up with a "1/2 inch" spark coil ... interesting (if somewhat politically incorrect) measurement units.


^^;;^^