Notes: "The model 0958 Geodat was Aristo’s most advanced slide rule for surveying. In addition to the usual C, D, CF, DF, CI, L, K, A, B, SIN and TAN scales (most labeled with their function rather than name), the 0958 has cos, sin • cos and cos2 scales, plus a P scale for sin-cos conversions, a special tangent scale for large angles, and 1-cos scales for stadia surveying using a horizontal rod. Also, there is a special scale labeled 1/tan(a/2) that can be used to calculate the hypotenuse minus the opposite side in a right triangle, and which also provides the capability to correct for Earth curvature and atmospheric refraction (note the ER hairline on the cursor). "