A special piece from the dawn of an industry and even before the incandescent light was perfected. The stamp has a bulb of sorts, with no set type of filament as there was no set type of filament yet. Of course you can see that the screw in type of bulb was long off. You have to imagine that there was nothing much to go on, as all was new and unexplored territory in the fields of science and innovation. In a year a bulb will be developed. But, it would take a few more years till an industry was developed around it.
So here enjoy a piece of history from the very beginnings of a revolution. The electrical revolution.