Full Details

Name and Model Number Flynn Universal Trigonometric
................. Formula Finder
Country of Origin USA
Date of Manufacture c. 1920s
Front Scales [ A ] B C [ D E ]
Back Scales  
Scale Length C D Scale Length: 29-cm
Type of Rule Disc
Construction Thin Celluloid with ivory grain. Double disk type with slots and cutouts in the top disk to reveal the scales and data on the bottom disk. With single transparent celluloid cursor.
Area of Use Generic
Comment Patented by George Ryan Flynn on Aug.22, 1922. This example probably has the longest name of any slide rule known, i.e. Flynn Universal Trigonometric Combination Semi-Circular Slide Rule-Protractor-Sine Table-Angle Formula Finder! Unique semi-circular bottom half and trigonometric function protractor top half. Note hand drafted minute details. Fitted leather case with gold lettering. Only 2 known examples known to me.
Rarity RRR
Donor Collection of Ed Chamberlain
Match Number 147
(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.