Notes: "This 12.5 cm pocket slide rule by MARC. The “UNIS FRANCE” marking is not a brand marking, it is a predecessor of the “Made in …” markings that we see today, but it was a bit more official. MARC is the only slide rule manufacturer known to have used the UNIS FRANCE marking. As a slide rule manufacturer, MARC (founded by Alphonse Adrien Fernand MARC around 1920) was very specialized, making only pocket slide rules. Their rules are always made of celluloid, are very thin (3mm, see the picture showing the slide rule and a US $0.05 nickel), and have a non-reversible slide. This one is a very simple Mannheim, having only A, B, C, and D scales. Most of MARC’s slide rules were advertising pieces. This one is advertising Chicago Pneumatic Tool Co. In 1931, MARC sold his business to Carbonnel et Legendre, who continued to manufacture slide rules with the MARC name on them. It is unknown what happened to Carbonnel et Legendre, but the MARC name could still be found on slide rule as late as the 1960s. This slide rule probably dates from the 1930s."
