Note the shape of the Viterite cone in the E27 Cap.....this is called a "Siemens Base". Note also the mica teat deflector is such a low power rated lamp.
G.E. sent out patent scouts to Hungary in about 1905 to purchase the Patents of Just and Hannaman which pertained to the fabrication of tungsten wire...this gave William Cooldige the go-ahead to really get stuck into tungsten metallurgy in the last part of the first decade of the 20th century.
Just and Hannaman's intellectual property stayed in Europe though as they had sold the rights to G.E.....what they founded later became Tungsram....but Siemens, which foundered Osram, was not sitting idly by...they initially tried tantalum, successfully too, but tungsten had the higher melting point. Not sure if they purchased Just and Hannaman's patent rights or simply applied what they had learned with tantalum to tungsten. At any rate, this is the result...a filament structure as advanced as any made by GE around the same era....but the pure nitrogen fill is far from perfect due to uts low molecular mass and relatively high thermal conductivity, (hence the mica disc in such a low power rated lamp) ...I think that quite a bit of Patent Litegation was goin g on at this time regarding fill gas compositions. Philips had a lamp called an "Arga" out at about this time, and it was filled with pure argon.