Reiche & Vogel
Blitzgerat
Used in an opera at Glyndebourne.
Description by Hugh Chinnick:
The Blitzgerat contains a light source similar to an electronic flash gun, but is focussable. There is a small neon on the back which indicates when it is charged, and a black button to fire. It can take three slides, inserted in the top, that sit one on top of each other. The middle slide is the one that will be projected. Pull out the bottom slide (there is a notch on the side to remove it sideways) and the other two drop down so what was the top slide is now in the middle position. Place the slide that was removed back into the top and continue the sequence after each flash. By rotating or reversing the slide the lighting image would be different each time. The small white socket is for a 'remote'. There's a wooden handle on each side.
Documents & Photos
From 
Full details about Blitzgerat ()