Hi Gutfinski,
What you have there is in fact a recycled lamp! Originally it would have been a Mazda cage type tungsten lamp. But in the early days a number of companies set up business in lamp repairing. The Sylvania company started out this way.
They would save old bulbs, cut off the tip, remove the old filament and stick in a new carbon filament, then reseal and pump it. You will notice that the tip on your bulb is somewhat wider than usual - this is because the hole had to be widened out to fit a new filament through it and some tools to maneuver it into place.
The recycling companies could only install new carbon filaments, because they are unsupported and could be fitted in through the hole of the tipoff. But they of course didn't care whether they recycled a bulb which was originally carbon or tungsten. Tungsten lamps just had the glass rod up the centre snapped off to make room for a carbon filament. I have a curios one here where they only removed part of the inner rod - it has filament supports at the bottom for the old tungsten filament, and yet a carbon filament is in the bulb - that one kept me confused for years as to what it was!
Mazda lamps were never made with carbon filamanets (except in the UK and France), so your lamp is certainly the recycled type. In fact you can still see a small stub of glass above the stem press, from where the original filament-supporting glass rod used to be attached.
James.
