harry wrote:

On Monday, 14 January 2019 07:12:58 UTC, D.M. Procida wrote:
I bought a lightbulb (and a ceramic holder and rotary lightswitch) in a
second-hand shop yesterday. They had many beautiful items taken from an
old electronics teaching laboratory - all brass, steel, ceramic and
wood.

The lightbulb:
https://www.dropbox.com/s/qw0vnqdtvemf0ld/lightbulb.jpg?dl=0.

It's about 10cm tall, and has an Edison screw. The filament loops up and
down the bulb in six lengths. It's made by Osram, but there are o other
readable markings on it.

Any idea what the purpose of a lightbulb like this might be?

I'm tempted to run it at low voltage to see what it looks like
illuminated, but I'd hate to damage the filament.

It's just old. Intended to go in a floodlight. n days of yore they
Icouldn't make reliable thin tungsten filaments so they had to be long.
It IS interesting.

So likely to be a high-powered, standard mains voltage bulb?

I assume it would not come to any harm run at a lower voltage, though I
know that some lamps can darken as the result of deposits on the inside
of the glass when run dimmed.

Daniele