On Mon, 14 Jan 2019 08:12:54 +0100,
(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.

Possibly a decorative low current lamp such as these modern version.

https://www.lightingstyles.co.uk/e27...ent-amber-lamp

https://www.dowsingandreynolds.com/s...long-filament/

The filament usually only glows, you can see the amount of slack in
them, anything much more than the power needed to make them glow would
also make them expand, sag and break.