A practical handbook that explains construction, operation, and repair of high-voltage coils and their accessories, with illustrated guidance on winding, insulating, and assembling primary and secondary windings. It describes various contact breakers, condenser designs, batteries and storage cells, and gives adaptations for spark coils used with gas engines and medical apparatus. Experimental chapters cover luminous discharges, spectral observation, vacuum-tube behavior, rotating discharge effects, and gas-lighting circuits, while appendices offer practical X-ray and wireless-telegraphy information, troubleshooting tips, and component specifications to support hands-on work.