Re: "em" should be horizontal, "ex" vertical

Peter Flynn (pflynn@imbolc.ucc.ie)
12 Aug 1997 13:59:50 +0100


Date: 12 Aug 1997 13:59:50 +0100
From: Peter Flynn <pflynn@imbolc.ucc.ie>
In-reply-to: <199708120529.WAA08087@germany.it.earthlink.net> (message from
To: davidp@earthlink.net
Cc: www-html@w3.org
Message-id: <199708121259.NAA01990@imbolc.ucc.ie>
Subject: Re: "em" should be horizontal, "ex" vertical

David Perrell writes:

   Your typographical history is wonderful, but is not "en (6pt)" a typo?
   Surely you aren't implying an en is 6 points?

Oops. A _pica_ en is 6pt..."an en" (unspecified) means half an em of
the current point size.

   Anyone who's used a typewriter more than occasionally knows there are
   two basic types: pica and elite. Pica is 10 characters per horizontal
   inch and 6 lines per vertical inch, Elite is 12 characters per

Pica was 12pt type, Elite was 10pt. These do indeed approximate to
10cpi and 12cpi respectively when used for fixed-width fonts like
early typewriters, which is why they were chosen: they were already
familiar names.

   horizontal inch and seven lines per vertical inch. (There's also a 15
   character per inch typewriter; can't remember what it's called.)

Minion, I think, was between 7 and 8pt. I have a list of them at home.

   Anyone who's worked in newspaper publishing knows an 'agate line' is
   one column by 1/14 inch. But why is it an 'agate' line?

All the old small sizes (up to 14pt) had names, and many of them were
of precious stones (pearl, ruby, etc). Agate was just over 5pt (none
of the sizes were exact, and one typefounder's size was not the same
as another's).

   In Medieval Latin, a pica is a collection of church rules.

This is a minefield: pica is the Latin for a magpie, the bird: it's
derived from the Sanskrit pekaa which is cognate with pinguu which
gave us the penguin; but pica also gave us our word "pie" (the food
encased in pastry; so called because it was a collection of oddments
or leftovers, such as a magpie gathers; and the "printer's pie" which
is a mess of undistributed mixed type, from which we get the
wrongly-named "pi font", which has nothing whatsoever to do with the
Greek letter pi and everything to do with bits and pieces, from which
it should be a "pie font"). 

Pica for the ecclesiatical rule is mixed: it embraces by metonymy the
collection of bits and pieces, the pecking backwards and forwards in
the complex regulations for the form of worship, and the corruption
into "pie" which in Latin also means "pious" or "holy". To confuse
matters, the Middle English for this use of "pica" was "pie"
(pronounced "pee-ay"): see Caxton's first advertisement
(http://imbolc.ucc.ie/~pflynn/caxton.html).

All of which gets us no closer to why a pica was chosen for 12pt type,
but possibly because it is clearly read, and the faithful needed to be
able to see what prayer came next. The fashion for printing Christian
books of worship in very tiny type is a much later invention.

   Why are there twelve points per pica? Western typography began
   (approximately 500 years after the Koreans invented moveable metal
   type) with the publication of Christian scripture, and twelve is a
   significant number in the Christian religion. Any correlation?

I don't think so. Most older societies used duodecimal (base-12) and
vigentisimal (base-20) counting systems in preference to decimal
(base-10), which only came in with the Romans. Anyone who lived in the
UK or Ireland before 1969 will remember the pre-decimal currency with
12 pennies to the shilling and 20 shillings to the pound. Despite the
apparent ease of calculation in base 10, it is actually much more
manipulable in metal arithmetic to use base-12 and base-20 because it
divides by many more factors than 10 does. Base-20 is also "normal"
for a human with 10 fingers and 10 toes (pace the old joke about the
man who can count to 21 stark naked :-)

When Gutenberg invented the casting of metal alphabetic types (I think
the Koreans used wooden syllabic ones) from molds punched into brass
with engraved steel, he was using his training as a goldsmith, and
that would have involved his knowledge of their traditional systems of
measurement in tiny increments for precious metals (units like
scruples and grains), some of which (I think) are also base-12.

Adherents of Erich von D&auml;iken's theories of earth's visitation by
extraterrestrials will have noted that one variant of the Mayan
calendar, based on the Venusian year, works on base-12, from which
they have deduced that Earthlings are mutated colonizing Venusians who
originally had 12 fingers and/or toes :-)

But we digress...

///Peter