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Re: Units of measurements

From: Jan Roland Eriksson <d.tek.jre@ebox.tninet.se>
Date: Mon, 06 Apr 1998 17:21:42 GMT
To: Todd Fahrner <fahrner@pobox.com>
Cc: www-style@w3.org
Message-ID: <35310ba1.6230919@pop.tninet.se>
On Mon, 6 Apr 1998 09:36:33 -0700, Todd Fahrner <fahrner@pobox.com>

> Thus spake Frank Boumphrey:
> >      em takes on a different meaning in CSS to the  usual typographic
> >term. In Typography, 6em's=1 inch,
> You must be confusing em with pica. A pica is 12 points. There are six of
> them in an inch. Only in a 12-point font is a pica equivalent to an em. As
> for em as a "usual typographic term", there's no end of debate on the
> connection to the letter em. Jan Roland Eriksson has produced a nearly
> exhaustive treatment here:
> http://home2.swipnet.se/%7Ew-20547/stylework/typograph1-en.html#Ch23 ...
> yet he disputes any historical connection to the letter M. I've heard
> otherwise, and will recycle a little ascii art from usenet:

There's an update coming to that page soon, where I have included
results of new reserch. I had to go all the way back to the old Roman
font "Capitalis Quadrata" as used in the Roman Empire for inscriptions
on statues and memorial monuments, to find the true connection between
the letter M and what later became the 'em' unit.

The 'em' seems to be first mentioned in monk handwriting instructions
originating in the period of 600-800 a.d. i.e. at the same time as when
lower case letters made their entrance. Already then it was specified as
a square area with side length equal to the font height in use.

Since lower case letters introduced decenders, fonts automatically
became higer than the previous "all caps" type of fonts. Thus the 'em'
lost it's connection to the widht of the capital letter 'M' at the same

A one 'em' (em-quad) first line indent is first used in monk
handwritings originating during 1200 a.d. when the monks stopped using
the "alinea" character to mark start of new paragraphs.

Jan Roland Eriksson - d.tek.jre@ebox.tninet.se
Received on Monday, 6 April 1998 13:25:37 UTC

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