Notes: "The Aristo 940 Stahlbeton System Göttsch slide rule was specifically for calculations related to reinforced concrete. The 940 was a latecomer to the slide rule market, being introduced in 1972, with its production overlapping with the earlier 939, which had been made since 1968. The 940 had 18 special-purpose scales for reinforced concrete, where the 939 had 8. While the 939 had a complicated cursor, the 940 raised that bar to new heights, with numerous lines, many of them curved, gauge points, and additional scales! This cursor is a work of art all by itself. Aristo closed and liquidated the slide rule production portion of the company in 1978, so the 940 would have had a fairly short production life. "
