Philips Historische Producten museum Eindhoven (33/52)

Here's a closeup shot of the business end of the model 6004S, a high-intensity cinema projection lamp that was used before the 1950s (see more details there). The lamp features a compact low-voltage (15.15 V) filament placed at the center of the half-mirrored spherical bulb extremity of the lamp. This kind of light source fell out of favor following the introduction of the xenon short-arc lamp in the early 1950s.