Notes: "This Davis slide rule is a standard Mannheim model with A, B, C, and D scales on the front, and S, L, and T scales on the back of the slide. The only gauge marks on the scales are Pi on the left side of the A & B scales, and Pi/4 on the right side, for finding the area of a circle. There is a ruler divided in centimeters and millimeters on the upper, beveled edge, and an inch ruler on the lower, vertical edge. "
