||This is believed to be one of the earliest U-shaped fluorescent lamps, having been made in 1950. The original inventor of the U-shaped lamp is not known, but in view of their popularity in Germany as well as the extensive product ranges offered by the German lampmakers Osram and Narva, it is suspected that the design may have originated there. Although Osram exhibited its first fluorescent lamps in 1936 (for neon sign illumination), the production of general lighting lamps did not happen until 1940, in very small quantities for the illumination of subterranean war factories. Osram's lampmaking activities were practically destroyed during the war, and key Eastern factories lost to the Soviet invaders which were amalgamated to form the Narva group. It was not until 22nd January 1946 that linear fluorescent production could restart, at Factory-S in Berlin. The first U-shaped lamps were produced there on 15th August 1949.
The nomenclature of early Osram fluorescent lamps is often difficult to understand, especially this type HNW-72 S. The first letter H refers to a Mercury discharge lamp. N=Niederdruck, i.e. Low Pressure. The third letter indicates the light colour where I = Incandescent, W = Weiß (white) H = Hellweiß (bright white), and T = Tageslicht (daylight). A suffix -Z is added in case of "Zweischicht" or double-coated lamps, having a second phosphor coating to improve the colour rendering quality. The number indicates the lamp model, the first digit indicating the main type and the second the variant. In this case, 7 is used for the 16W rating and 2 refers to the second variant, in this case meaning the U-shaped variety. The last letter S in a square box refers to the type of ballast. Each German ballast used to have its own unique letter identifier.