Gas Street Lamp - 1853

This model of gas lamp was used in Stockholm between 1853 and to the 1940s.
In 1897 there were about 6600 gas lamps in the city streets.
You can still find this lamp type in the Stockholm old town, but today electrified.

A gas flame have a luminous power corresponding to about twelve candles (= 12 Candelas, -cd). The lighting effect was drastically increased when in 1897, the gas mantle was introduced.
This invention consisted of a sock that glowed from the heat of the gas lid and gave off a strong white glow. The mantle consisted, among other things, of Thorium, which also made it radioactive (radon gas was formed).
With the help of this sock, however, the light output of the gas lamps tripled.