Slide rule scale names

Edward Dean Butler

Not long ago there was a discussion within this group about the earliest use of scale markings, such as A, B.

Today I was looking at a copy of Thomas Abel’s 1761 book “Subtensial Plaln Trigonometry, Wrought With a Sliding-rule, With Gunter’s Lines.” The slide rule illustrated therein is two separate scales sliding one against the other. Both scales are standard two cycle scales and are labeled A and B.

E Dean Butler
Broughton Green, UK

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