Carbon wire filament incandescent light bulb

The base of this carbon filament light bulb is characteristic for Siemens & Halske and is also called a ‘duck foot’. Carbon filament lamps were the first incandescent light bulbs, in which a filament emits light when heated by an electric current. The filament must be kept in a vacuum to prevent it from burning up, and this is why the filament is enclosed in a glass bulb.