Dear All,
I have just been doing some additions and editorial clean-ups to my
chronology of the metric system at: http://www.metricationmatters.com/docs/MetricationTimeline.pdf
and I thought that you might be interested in these two additions
that most of us have to contend with every day as we lay out pages on
our computers.
1737
Pierre Simon Fournier (1712/1768) began to use the point as a
typographical unit for measuring printer’s type. Fournier’s published
his printing ideas in his book Manuel Typographique. As Fournier lived
and worked in France his point size was defined as 1/72 of the French
Royal Inch of about 27.1 mm (1 Fournier point ~ 376 µm). Later
definitions used inches with different lengths; English typesetters
used the English inch of about 25.4 mm but kept the 1/72 fraction thus
giving English typesetters a point with a different, smaller, size.
The English point is defined as about 0.013 888 888 … inches (~ 353
µm). Later Nelson C. Hawks (1841/1929) of California redefined an even
smaller printer’s point as 0.138 exactly or 351 µm (see 1868 below).
Benjamin Franklin was appointed Postmaster for Philadelphia in 1737.
Later, Benjamin Franklin owned a copy of Pierre Simon Fournier’s book
Manuel Typographique, which he probably purchased from directly from
Fournier when Franklin was in France as a diplomat between 1776 and
1785.
1868
Nelson C. Hawks (1841/1929) of California redefined the printer’s
point to exactly 0.0138 inches by rounding it down to avoid the
recurring 8s that occur when you define a printer’s point as exactly
1/72 of an Imperial inch (1/72 = 0.013 888 888 …). In doing so Hawks —
probably inadvertently — redefined the inch as about 0.9936 Imperial
inches (25.237 44 millimetres instead of about 25.4 millimetres).
Hawks printing point was now only approximately 1/72 of the Imperial
inch used in the USA at that time. The Association of Typefounders of
the United States convention in Saratoga officially adopted Hawks’s
point system as a national standard in 1868.
When computer programmers first met all of this old printers jargon
they tried to adapt it to modern computers. Some chose to use the
fraction 1/72 and to base their point on that value without knowing
that this applied to various old pre-metric inches; others chose the
imperial inch as their standard and modified the fraction 1/72 a
little to make it fit. Needless to say we now have a choice of old pre-
metric points that are post-modern in their retrofitted construction.
Here are the main ones available today — with their approximate value
in whole micrometres:
* 1 point (ATA) = 0.3514598 mm = 0.0138366 inch
o 351 micrometres
* 1 point (Didot) = 0.3759 mm = 1/72 French Royal inch (27.07 mm)
= about 1/68 in.
o 376 micrometres
* 1 point (l'Imprimerie nationale, IN) = 0.4 mm
o 400 micrometres
* 1 point (Postscript) = 0.3527777778 mm = 1/72 inch
o 353 micrometres
* 1 point (TeX) = 0.3514598035 mm = 1/72.27 inch
o 351 micrometres
* 1 point (Truchet) = 0.188 mm
o 188 micrometres
Cheers,
Pat Naughtin
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
helped thousands of people and hundreds of companies upgrade to the
modern metric system smoothly, quickly, and so economically that they
now save thousands each year when buying, processing, or selling for
their businesses. Pat provides services and resources for many
different trades, crafts, and professions for commercial, industrial
and government metrication leaders in Asia, Europe, and in the USA.
Pat's clients include the Australian Government, Google, NASA, NIST,
and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com/
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