My  guess is that the 1/6 and 1/12 inch divisions are useful for page layouts, 
figuring 72 picas per inch. If I recall, that makes a 12 point em equal to 
1/6 of an inch.

I'm lost on the 5/32 inch divisions but two things come to mind. First, that's 
darned close to 4 mm! More likely though is that it would provide a leading 
allowance for 1/8 inch tall (9 point) type.

Jim

On Tuesday, 2004 January 13 00:52, Bill Potts wrote:
> That's a very broad question, because there are so many kinds of rulers.
>
> I have a Canadian steel ruler from the early 1970s with two scales on each
> of two sides. On one side, one edge is graduated in 5/32" units, with the
> other edge in inches, subdivided into 1/6 and 1/12. The inches themselves
> have two markings -- 1, 2, 3, 4, etc. and 6, 12, 18, 24, etc.
>
> On the other side, one edge has inches in 1/10, with each 1/10 individually
> marked from 1 to 150. The other edge has inches with 1/4", 1/8", 1/16" and
> 1/32" subdivisions. The inches themselves are marked 1, 2, 3, 4, etc. and
> 150, 300, 450, 600, etc.
>
> The ruler has other features I won't mention yet.
>
> I want to see who can guess what kind of ruler it is, what some of the
> numbers mean, and what the other features might be. One clue is that, in
> spite of having no metric units whatever on it, it is still useful and the
> units (and features) still have a valid purpose.
>
> Think "legacy systems."
> Bill Potts, CMS
> Roseville, CA
> http://metric1.org [SI Navigator]
....
-- 

James R. Frysinger
Lifetime Certified Advanced Metrication Specialist
Senior Member, IEEE

http://www.cofc.edu/~frysingj
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