The 21st Edition General Catalog (all revisions) was arranged as nine separate catalogs (Drawing Instruments, Slide Rules ,etc) all bound together.  This facilitated issuance of separate speciality catalogs.  The slide rule sub-catalog consisted of an un-numbered cover page and pages 78-88.

The first revision listed eight Frederick Post brand slide rules--models 1441, 1444K, 1447, 1452W, 1460, 1461, 1490 and 1491.  The third and fourth revisions added model 1450.
 

General Catalog

Slide Rule Sub-Catalog