Archive of Collections

Archive of Collections

Details and Image

Item#	Type	Model No.	Match No.	Variant No.	Model Name	Maker	Country	Production or Serial No.	Material	Scale Length	Date	Condition
KEU250	Linear	Mystery	4724	1	Mystery Polyphase Mannheim	Keuffel & Esser	USA	774832	Engine divided celluloid laminated mahogany	"20"	1941	C7

Notes: "Mystery 20" slide rule with scales: A [ B CI C ] D L on front, [ S A T ] on reverse of slide, and unlabelled K scale on bottom edge. Top edge has a centimeter scale in place of the normal inch scale on 20" slide rules. USBS Circular 47 version of conversion table."

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