Post doesn't seem to have recovered from the disruptions of WWI. They offered only three "Frederick Post" brand slide rules in the 1921-22 catalog and I don't believe that two of them were actually availalbe for purchase. ( See Models 1444A-C. ) This is the one you could actually buy.
I have also seen a variant of this model with just "FREDERICK POST CO." in the gutter and a different table on the back. (Columns: "Division of 90 deg.", Division of 100 deg.", etc.)
Both variants were manufactured Koch, Huxhold & Hannemann.
|This slide rule is listed in two sources:
(1) The 1921 and 1922 Post Catalogs
(The "Sectional View Showing Construction" appears to be derived
from an illustration in the 1910 Post catalog and 1906-1919 Dennert &
Pape catalogs. I'm sure it was supplied to Post by a German manufacturer
but I don't think it came from KHH.)
(2) "Instructions for Calculating Slide Rules" c1923-24