K&E 4180 Fraction Adder

Description:

K&E 4180 Fraction Adder is a specalized linear slide rule for adding fractions. It is circular in form.

History:

The 4180 was first shown in the 1913 hard bound catalog. It did not appear in the 1913 soft bound catalog. It last appeared in the 1915 catalog.

Scans of a 4180 from an eBay sale in Dec. 2002: