This list contains rules for which to date I have not been able to positively identify their makers. (Assuming the other identifications within the collection have all been “correct.”)
Total number of unidentified slide rules in the collection: 5.
||1880||wd||9.0||no||nice boxwood Comparative Rule for alcohol taxation, likely from a Sikes’ hydrometer set; one side does comparative values; other side does reducing calc|
|1919||wd||5.0||yes||5-in pocket rule; on back: C.E. Brignell, Coblence, Germany, Sept. 1919; D&P pi symbol?|
||1928||ss||5.5||no||Engraving Proportion Scale; sold by Art Brown & Bro. Inc. NewYork; similar item on MIT Museum page|
||1960||wd||12.0||no||18 inch proportions rule, used in printing, engraving; maker? American Blueprint?; A/B scales range from 1 to 30, 12 inches from 1 to 10|
||1970||pl||5.0||no||Made in Japan; ALCO?; from my high school years|