Illumination items: By the lighting and illumination committee: Relative performance of tungsten filament lamps under test upon alternating and direct-current circuits

Drawn wire tantalum filament lamps suffered from crystallization and offsetting so seriously as to restrict their use very generally to direct-current circuits, where these effects were not so pronounced. Drawn wire tungsten filament lamps suffer from similar effects of alternating-current operation, although the manufacturers of Mazda lamps have succeeded in treating the filament in such a manner as to diminish the difficulty to a point where it is of academic rather than practical interest.