Hi Bill,
Thanks for emailing. I’ve read through the discussion and will add to it when I have some time to get my thoughts together. Quickly I can confirm that the majority of all light bulbs manufactured before about 1910 that utilized carbonized filaments all had a vacuum atmospheres (with some rare exceptions.) Around 1910 or so (again I don’t have any reference material in front of me) the use of tungsten filaments came into being. Someone discovered at this time that if tungsten filament bulbs were filled with a mixture of gas (such as nitrogen and argon) their efficiency could be increased, giving way to smaller tungsten filament bulbs that were highly efficient. Prior to this, the only tungsten bulbs made were large high wattage types since anything smaller would not be efficient over the older carbon types. When I get some free time I’ll try and reply with a clearer and more detailed explanation. Today the modern tungsten filament light bulb is gas filled as someone pointed out on your forum but it wasn’t always that way!
Regards,
-Tim Tromp
(Kilokat7)
www.BulbCollector.com 
