Full Details

Name and Model Number	Sexton's Omnimetre
Country of Origin	USA, Philadelphia
Date of Manufacture	c. London 1895, c. USA 1898
Front Scales	A, B, trigonometric scales
Back Scales	none
Scale Length	A scale 18.8 inches
Type of Rule	Disc
Construction	Two flimsy cardboard disks in 8 inch square wooden box
Area of Use	Generic
Comment	“Numeri mundum regunt”, printed on lower scale = “numbers rule the world”
Rarity	RRR
Donor	Collection of Clay Castleberry - California USA
Match Number	278
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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.