The Turn Of The Century Electrotherapy
Experimental Pancake Coil for Brush Discharges
Winding pancake coil...
Coil embedded in paraffin wax / boiled linseed oil / kerosene mixture
placed above primary coil from Thomas Stanley Curtis Reproduction
Large volume of violet brush discharges, sparks are roughly the same length and colour
A similar but earlier spark gap diathermy Prostate Electrode