Full Details

Name and Model Number Hiltpold
System Ing. E. W. Hiltpold
Country of Origin Switzerland
Date of Manufacture During and just after WWII.
Front Scales A [B C] D L 360° scale
Back Scales K S T ST
Scale Length About 14 cm (CD scales)
Type of Rule Disc
Construction Transparent plastic rotatable scales. White plastic fixed scales. Aluminium core.
Area of Use Generic
Comment Walter Hiltpold (1897-1945), a Swiss engineer from Zürich, obtained two Swiss patents for what he called a Kreisnomograph (circular nomograph); N° 228237 was applied for in 1941 and N° 227376 in 1942, both patents were granted in 1943. Two sizes of this quite clever circular rule are known to have existed, the one pictured is the smallest one (100mm x 75mm overall dimensions). The scales are laid down only on a portion (235°) of the circle. Notice the 360° scale meant to measure angles.
There was an instructions booklet printed in German and a translation of it in French.
The early death of the inventor might explain the rarity of this slide rule.
See article by Paul Wirz The semi-circular slide rules of Walter Hiltpod in the proceedings of the 4th International meeting of slide rule collectors (available through http://sliderules.lovett.com).
Rarity RR
Donor Photo from a collection in Belgium
Match Number 341
(Click Picture for Details)

In conjunction with our 'donors' we assign a rarity rating to each item, based on the system devised by Herman van Herwijnen
(1929 - 2004), renowned Dutch collector, author, and creator of Herman's Archive, a collection of 5,000 slide rule images on CD.
• RR = Rare - 1 of 25 collectors has one; it may take a year to find an example in the marketplace.
• RRR = Very Rare - only a few known to collectors; may be several years before it comes up for sale.
• RRRR = Extremely Rare - a museum piece; unlikely that an example will come up for sale.