Glow-lamp of unknown brand, I have a few. The glass tip
on the top points at an oldie: that time the manufacturers couldn't produce
the bulb without this glass nipple. It should be about 100 years of age now.
The inside of the glass looks a bit black. I guess the charcoal filament evaporates and precipitates to the inside of the bulb.
This was my first attempt to make an animated GIF-picture. I shot 9 pics of the bulb, starting with a voltage of 30, and with each picture I raised it with 10V. I stopped at its nominal value of 110 volts, at that point it produces 16 candles of light. The camera I used was the digital Samsung on the tripod of course. Resolution is 640x480 pixels, and I only used some 10% of each picture. The camera decides how much light is needed for the image, there's nothing to adjust. A disadvantage in this case. The background lighting was achieved by a fat 500 Watts UV-lamp because this was the nearest.