Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!samsung!think!bbn!news
From: news@bbn.COM (News system owner ID)
Newsgroups: comp.lang.postscript
Subject: Re: ruler.ps - an inch/point ruler of your very own
Message-ID: <50949@bbn.COM>
Date: 16 Jan 90 13:20:40 GMT
Organization: Bolt Beranek and Newman, Inc., Cambridge, MA
Lines: 49

Reply-To: cosell@BBN.COM
Followup-To:
Organization: BBN Systems and Technologies, Inc, Cambridge, MA
Keywords:
From: cosell@bbn.com (Bernie Cosell)
Path: bbn.com!cosell

In article <1990Jan15.183143.7677@intercon.com> amanda@mermaid.intercon.com (Amanda Walker) writes:
} In article <1990Jan14.180821.18711@trigraph.uucp>, bruce@trigraph.uucp (Bruce
} Freeman) writes:
} > The great thing about points is that there are so many of them to the inch.
} > PostScript has decided that there are exactly 72 to the inch but the industry
} > standard is generally that there are 72.3 points to the inch.
} 
} It's actually even worse, especially if you take European conventions
} into account.
} 
} "Conventional" Amrican		72.27 ppi
} PostScript and some others	72 ppi
} Didot point			67.54 ppi
} 
} And then there's the pica (12pt), which is therefore sometimes 1/6th of an
} inch, and sometimes 1/6.022th of an inch, the cicero, which is 12 didot
} points, ...

You've left the original definition of the point (by Fournier in 1764) out of
your list:
    At the head of the table is a fixed and standard scale which I have
    divided into two inches, the inch into 12 lines, the line into 6 of these
    typographical points, making 144 points in all...

Didot actually _tried_ to define a point that was the same size as
Fournier's, but defined his point to be one-72nd of a *french* foot
[do the french ALWAYS insist on inventing their own standards for
things???  :-):-)].  

The "conventional American" point IS kind-of metricized: The 1886
standard from the United States Type Founders' Association was based on
the observation that the American-pica had an almost-relationship to
the cm:

     83 picas ~= 35 cm

and so they standardized on exactly "83 picas = 35 cm".  They then
defined the 'point' to be 1/12 of a pica.  THAT's where the funny
decimal at the end came from --- you can thank a metric-conversion for the
non-integral value.

  /Bernie\