Notes: "This is quite an early Dietzgen slide rule, based on the construction, the upper and lower stators are joined only by a single large piece of celluloid, one side of which is visible in the well under the slide, and the other side on the back. The font of the scale labels, “A”, “B”, “C”, and “D” is also reminiscent of John Davis / Dennert & Pape. The large serifs, especially on the “A”, are very distinctive; D&P may have been the maker of this Dietzgen slide rule. "
