K&E 4165 Urea Index Slide rule

This slide rule is a specail function rule built on a Mannheim frame. The rule is best described on page 246 of the K&E full line catalog from 1921. This rule is only shown in the 1921, 1922, and 1925 catalogs.

These scans are from the collection of Clark McCoy

Front side and case:

Back side of rule and slide:

Top edge of rule

Bottom edge of rule

Left end of rule