I came across two very old light bulbs the other day. Take a look at this first one and notice that the vacuum exhaust tip is on top of the glass envelope, away from the threaded base. It looks like the kind of exhaust tips you would see on vacuum tubes of days gone by like the 6AU6 or the 12AX7.
The second bulb is a bit more modern as its own exhaust tip is apparently hidden inside the threaded base.
It's also interesting to note that the name "Edison" isn't there anymore eiher.
Taking a closer look at that second bulb however, we see something that is there and which quite surprised me. There is a gas bubble in the glass.
The filaments in both bulbs are open so I'm guessing that they each delivered light for their respective service lives and that the trapped bubble in this one apparently did no harm.
Today, these bulbs are just a couple of curios, I suppose. Still, is there a quality lesson in here someplace?
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