I wrote: >The ruler is 15", not 12". Fifteen inches used to be a fairly common length >for the continuous forms (especially the wider ones) that were printed, >bound, and then used for reference purposes. (No display terminals >or PCs in those days.)
More important, though, is that the 1/10" scale (for which every 1/10 is number from 1 to 150) was used for print layout for printers with 80, 120, 132 or 144 print positions. The IBM 407 tabulating machine had 120 print wheels. The IBM 1403 chain printer and its higher-speed successors had 132 print positions. The IBM 1443 printer had 144 print positions. Of course, design forms were used for forms design. They were lightly printed with rectangles 1/6" high and 1/10" wide, with print positions across the top. The exact same forms were, of course, used in metric countries, owing to the all-pervasive influence of companies like IBM, NCR, etc. Bill Potts, CMS Roseville, CA http://metric1.org [SI Navigator]
