Full Details

Name and Model Number Lawrence S.R. Co.
Lumber Calculator
Country of Origin USA
Date of Manufacture Est. 1940-1950
Front Scales Thickness in inches, width in inches, length in feet, board feet of lumber
Back Scales None
Scale Length 23 cm (9 inches)
Type of Rule Slide Rule
Construction Wood with white paint and black scales, magnifier cursor.
Area of Use Other
Comment Used for calculating board feet in any sized timber or board. Inexpensively made like most of the Lawrence rules
Rarity RR
Donor Collection of Clay Castleberry
Match Number 354
(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.