Darmstadt -- Aristo 967U

Germany, simplex, 25 cm scales, plastic.
In 1924 the Darmstadt slide rule was introduced by Dennert and Pape, based on a scale set designed by Prof. Dr. Alwin Walther, and has the addition of log log scales and a P scale.
On a simplex body, this rule handles all mathematical functions found on general purpose slide rules.