ID: 
1929
Maker's Name: 
Osram
Where made: 
England
Dimensions: 
3.5 × 3.5 × 16.8 cm

This lamp has a discharge tube which vaporises sodium under low pressure, and produces light with a yellow tinge, characteristic of the sodium ion. The tube is operated from the AC mains through a ballast (inductor) to limit the current drawn.