Notes: "This is a standard Mannheim slide rule, and the patent number in the well indicates it was made by Dennert & Pape of Altona, Germany. The front face has the usual A, B, C, and D scales, and the back of the slide has S, L, and T scales. The most interesting thing about this slide rule is that it has a gauge point at 1146 on the A and B scales (look for the line that connects two red dots, one faded). This is commonly called the “Gunner’s Mark” and equals (180 x 60)/p x 3. "