Dumont

Data:

• Five metal discs, each covered with handwritten paper, with the three rotating discs fitted with fine brass knobs.
• All discs have a linear scale: the two inner ones running from 0 to 24, the three outer ones from 0 to 60. This scale could indicate that the slide rule was used for time calculations.
• Marked on the back, behind the anti-slip mat, “DUMONT 1935” (1935 is probably an inflated serial number)
• Stored in a 19 by 19 by 7 cm wooden box
• Previous owner: Reinhold Rehbein from Monheim (Germany), who bought it in France.
• More than 15 years ago, a Dumont calculating disk was offered for sale at an auction at Sotheby's or Christie's.

Questions:

1. How does the Dumont calculating disk work and what was it used for?
2. Is it known exactly where and how many of these calculating disk were made at the time?
3. Are there any individuals, institutions, universities, or museums that own a Dumont calculating disk?