Toshougu Copper Lanterns

At the Toshougu Shrine from Ueno, Tokyo, in front of the Karamon gate, there are 50 big copper lanterns, alongside the alley which leads to the shrine. All of them are offerings from daimyo, and the name of the donors are written at the base of the lanterns.
It is said that these lanterns were not used for lighting, they were lit just with sacred fire, for purification ceremonies...