7.7 Numerous Scales
Here we list the slide rules that have the largest number of distinct scales, presently those with 24 scales or more. We designate as a single “scale” a single line or path that extends across the length or circumference of the rule without interruption. Certain scales, for example the Log-Log scales, are often broken up into a series of scales; so, one could argue that a 25 cm slide rule that breaks a Log-Log scale into four parts (LL0, LL1, LL2, and LL3, say) has a 100 cm Log-Log scale. For this list, however, we are treating these as four separate scales. On the other hand, a spiral Log-Log scale that wraps around a circular slide rule 5 times would be designated as a single scale. Measurement scales (inches, centimeters, etc., mostly found on the older rules) are not counted in the sum.
|Boykin||RotaRule Model 510||S||1965||24|
The mean number of scales on the rules of the collection is 13.4, with a median number of scales equal to 11. Below is a histogram of the number of scales found on the slide rules of the collection. Note the bi-modal nature of the distribution, which shows a large peak at about 8 scales, and another distinct distribution centered at about 22 scales. One might argue that the distinction between a “basic” slide rule and an “advanced” slide rule is showing up. (See Why Slide Rules?.)