|Name and Model Number
|Calculigraphe Model F-C
|Country of Origin
|Date of Manufacture
|Type of Rule
|nickel or German silver
|Area of Use
|This is the model F-C with the castle logo rather than the opisometer on the more common model H-C.
There are fewer than 6 known in hands of collectors.
|Collection of Clay Castleberry
(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.