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36All About Slide RulesNote: Some older slide rules do not have scale labels. Click HERE to viewChapter 10, a list of 24 common slide rule scales and their functions.The slide rule shown is an Aristo 89 Rietz, 12.5 cm scale length, plastic, 10scales, simplex, Germany. It is a typical closed body type of slide rule with theRietz scale set, popular in Europe.Naming the ScalesThe naming of slide rule scales was possibly the biggest design flaw in anotherwise wonderful work. It would have made far more sense to call the scalesx, 1/x, x 2 , x 3 , etc., and some rules are made that way, particularly the FrenchGraphoplex rules. For reasons lost to history, the scales ended up withmeaningless letter names, especially A, B, C and D. It is likely that they firstappeared to make it simpler to produce written instructions, as it can be verydifficult to refer to the scales with no names at all, especially for a new user.Some scales have no real reason to have the names they do; certainly K forcube is a stretch, but L for Log makes sense, as does S for Sine, and T forTangent, and the added I for inverted or F for folded.Many European and Japanese rules became “self-documenting” with thefunction added at the right end of the scale (x, 1/x, etc.), and the scale nameletter appearing on the left end. This trend was not adopted in North Americadue to an attitude best summed up by the Pickett company, who felt that anyonesmart enough to use a slide rule didn’t need it. This user-hostile attitudewas to carry over into the calculator and computer software disciplines tofollow, a perpetual justification for poor user interface design. In Europe, thefocus was to create the best possible tool, and their sophisticated but easy to usedesigns certainly reflect that attitude.How to Read the ScalesRead the digits, then determine where your decimal point goes.All the basic scales start and end with the digit 1.