Mazda 'Vite' Mild Ultraviolet Daylight Incandescent
The BTH-Mazda 'Vite' lamp was introduced shortly after the development of the 'CX' ultraviolet incandescent lamps by its parent company GE in America, and their improvement by IGE's German subsidiary, the Osram company. It bears construction features attributable to each of these.

At the time of its introduction there was a belief in the medical world that many ailments could be alleviated by exposing the human body to fresh air and sunlight. Spending long periods of time under artifical lighting indoors was not considered healthy. The lampmakers invested considerable research in developing better lamps to mimic the full spectrum of sunlight. This required the addition of ultraviolet rays alongside the usual infrared and visible wavelengths.

The original 'CX' lamps achieved this thanks to driving the filament hotter so as to increase its proportion of ultraviolet radiation, and by using a new kind of glass bulb having superior UV transmission. In 1927 German Osram improved the daylight-simulating qualities by using a blue-tinted glass which increased the colour temperature closer to that of sunlight, while still transmitting UV-A and UV-B to just under 300nm. This particular lamp is a British-made version of the Osram development. It has a compact filament and an unusually short neck, being intended for use in a narrow-beam parabolic reflector to irradiate the body. In addition to therapeutic applications, the catalogue indicates that its spectrum is ideally suited for the lighting of indoor gardens. However, both the Mazda Vite and Osram Vitalux were not especially successful due to their weak UV content. As soon as more powerful UV lamps such as the Osram Ultra-Vitalux became available, they were quickly superseded.
Manufacturer: The British Thomson-Houston Co. Ltd.
Lamp Power: 150 Watts
Lamp Voltage: 230 Volts
Lamp Current: 0.65 Amperes
Cap Type: E27s/27 Brass & Vitrite
Bulb Type: P-80 P-25 in eighths/inch
Bulb Finish: UV-transmitting Inside frosted
Filament Type: C-7A Single Coil Wreath-Vee
Atmosphere: Argon-Nitrogen Red P getter
Luminous Flux: 1500 lumens
Luminous Efficacy: 10 lm/W
UV-A Flux: 0.2 Watts 320-400 nm
UV-A Irradiance: 16.5 mW/m2 @ 1m Mean horiz. irradiance
Colour Temperature & CRI: CCT: 3275K Ra 98
Chromaticity Co-ordinates: CCx: 0.416 CCy: 0.392
Lifetime: Estimated 500 hours
Burning Position: Base down to horizontal
Overall Length: 115 mm 41/2 inches
Light Centre Length: 76 mm 3 inches
Factory: Rugby England
Date of Manufacture: 1939 July Date Code: 67
Original Value: GB £0 22s 6d (1941)
References: 1) BTH-Mazda Lamp Catalogue, UK, 1941, p.18.
2) Photometric Measurement in Integrating Sphere for visible spectrum, and Spectroradiometer for UV spectrum.
3) Die Entwicklung Neuer Künstlicher Lichtquellen, A. Rüttenauer, Technisch-Wissenschaftliche Abhandlungen aus dem Osram-Konzern, 1931, pp.77-82.
4) 100 Years of Osram, Brand Centenary commemorative book, 2006, p.36.