Slide rule workshop

Fred Astren's mystery slide rule

S A German Soho?

Click images for magnification

The front of the slide rule
A detail with the only identifying marks
A detail of the indicators for reading the reverse of the slide

Data:

  • Early Soho configuration made of boxwood
  • Brass chisel-edge cursor
  • 25-cm scales
  • The body length is 27 cm.
  • Reverse of the slide is marked: “SINUS”, “TANGENT”, and “LOGAR”).
  • Purchased it on eBay Germany in 2016 from a seller who lives in a village in Bayern.

Question:

  1. What is this?