The Slide Rule Trading Co., Paul Ross

Hemmi Slide Rule Catalogue Raisonne

Also Sold As

Instead of using the Hemmi name and model numbers, some distributors sold Hemmi slide rules under their own brand name and model numbers.  Some of these brand name and model numbers are noted in the Catalogue Raisonne.  Abbreviations used are:

Post
The Frederick Post Co., Chicago.  1931-1970. 
T-P
Teledyne Post.  1970 +.  (Teledyne Post continued to use the "Post” brand name and model numbers in 1970-72.)
H-O
Hughes-Owens Co., Montreal. 1914–64.
Geo
  Geotec.  Hughes Owens changed its model numbering system in 1964 and changed the brand name on its rules to “Geotec” in 1968/69.  All rules that use the 1964 numbering system are identified as “Geo” even though rules sold between 1964 and 1968 actually carried the Hughes-Owens brand name.
USBlue
United States Blueprint Co., Chicago.  (1930s)
Lietz
The Alfred Lietz Co., San Francisco. (1930s)
Tamaya
Tamaya and Co., Tokyo.  (1913 - )

Hemmi continued to manufacture some models for these distributors long after those models had become unavailable under the Hemmi brand name.  For example, Hemmi sold a 20-inch simple Mannheim rule as its model 5 slide rule from about 1919 to 1927 but the same slide rule appears in Frederick Post catalogs as late as 1940 and in Hughes-Owens catalogs through 1948.