4-Inch Mannheim Slide Rule with Vertical Edges
Frederick Post model 1437  [1936-40]
Hemmi model 35.

Appears in 1936 Catalog and Price Lists through 1940.

Top edge (vertical) : 0-4 inches
Bottom edge: 0-10cm
Back of slide: [S, L, T]
Back of rule: THE FREDERICK POST COMPANY  No. 1437
Paper Table?

This page is from the 1936 (18th Edition) Post Catalog 

Same as Post model 1440 (Hemmi 30) except that the top edge of  model 1440/30 is slanted whereas the top edge of this rule is vertical.