Do a little research and find out how long gas lights (street lights) were used. And when did electric bulbs start to replace gas lights. That will give you an idea of it's age. I'm guessing 1900-1920.
Do you see a company name on it or serial number or any markings?
CS1969, To my surprise after cleaning it,no markings or info,of any kind.My thinking on the age was like yours on the transfer of lighting.But that would only give me the end of one era and the start of the other.Thanks ill research the start of the first