||Soon after the invention of the tantalum lamp in Europe, the news caused great concern among American manufacturers, who had performed no significant research of their own on metal filament incandescent lamps. The risk of losing their dominance to superior imported lamps was high, especially for General Electric, which together with National had operated a near-monopoly in the Americas since 1901.
In 1904 Siemens & Halske offered GE the American rights to its invention for a high price, but GE declined owing to the reduced life of tantalum filaments on AC circuits. However even on AC the tantalum lamp outperformed carbon, and the level of threat was such that GE eventually conceded. On 10th Feb. 1906 for a payment of $250,000, GE secured the exclusive American rights for itself and National to produce the lamps on a royalty basis. All of the American-made lamps were produced with tantalum wire sourced from Berlin.
This situation caused enormous stress within GE, because its research laboratory had been established precisely to maintain a leadership position which would avoid paying competitors for the use of lighting-related patents. To make matters worse, the situation was repeated when it again had to license the European sintered tungsten technology. However its high price meant that GE's tantalum production continued until 1910, after which Coolidge's development of ductile tungsten entirely displaced both tantalum and sintered tungsten from the USA market. This particular lamp has a rather unusual filament formation, with three instead of the usual two sets of carriers. Its purpose is perhaps to improve vibration resistance, or to achieve a mount of shorter length and higher brightness than with ordinary tantalum lamps.