Back Matter on Closed Body Slide Rules
My interests are mostly Hemmi and Frederick Post slide rules so this discussion
centers about those two brands.
Bureau of Standards Circular 47
United States Bureau of Standards Circular 47 was issued in 1917 and became
almost the standard table for the back of closed body slide rules.
Frequently the acknowledgement of USBS Circular 47 is omitted but the number,
layout and typography are almost identical on every slide rule that uses
it. It is so common that this website uses short phrases like "USBS
Circular 47 on Paper" to indicate this table on paper glued to the
back of the slide rule. USBS Circular 47 was used on the back of Frederick
Post rules made by Grafton Plastics, The Roos Company and Albert Nestler.
Table of Constants
All closed-body Frederick Post brand rules from 1925-30 were made by Koch,
Huxhold & Hanneman. Most of them carry a paper "Table of Constants:"
Note "THE FREDERICK POST COMPANY" in the upper right corner and "Pat'd. U.S.A.
1/31/22" in the lower right corner.
KHH rules made for English-speaking countries from 1925 and earlier use
a paper table titled "Slide Rule Data Slips." (That's
a good way to identify rules made by KHH; they can be easily mistaken for
Dennert and Pape Aristo slide rules.) "Slide Rule Data Slips" appears
on a few Frederick Post rules from the 1925-30 period--likely before Post
provided the "Table of Constants"--and at least one KHH-made Frederick Post
rule from about 1921-24.
Hemmi-made closed-body Frederick Post rules carry a table printed on thin
plastic slipped between the stators of closed body rules. Such tables
were not firmly attached and many have been lost. Special-purpose
rules had special-purpose tables but general purpose rules usually had this
table derived from USBS Circular 47: