Quad (typography)

File:Mquad-nquad-middlespace-comparison.svg in letterpress typesetting. In yellow is the cast metal sort name, and in black the corresponding Unicode whitespace character name.|396x396px]]

In typography, a quad (originally quadrat{{cite book | isbn = 1871516234 | title = Computers and Typography, v.1 | last1 = Sassoon | first1 = Rosemary | year = 1993 | publisher = Intellect | page = 40 }}) was a metal spacer used in letterpress typesetting. The term was later adopted as the generic name for two common sizes of spaces in typography, regardless of the form of typesetting used. An em quad (originally m quadrat) is a space that is one em wide; as wide as the height of the font. An en quad (originally n quadrat) is a space that is one en wide: half the width of an em quad.

Both are encoded as characters in the General Punctuation code block of the Unicode character set as {{unichar|2000}} and {{unichar|2001}}, which are also defined to be canonically equivalent to {{unichar|2002}} and {{unichar|2003}} respectively.{{cite web|author=Jukka Korpela|title=Unicode Spaces|url=https://jkorpela.fi/chars/spaces.html|access-date=2013-09-18}}{{cite web|url=https://www.unicode.org/charts/PDF/U2000.pdf|title=The Unicode Standard, Version 6.2: General Punctuation, Range 2000–206F |author=Unicode Consortium|access-date=2013-09-18}}{{Cite web|title=Unicode Mail List Archive: RE: Difference between EM QUAD and EM SPACE|url=http://unicode.org/mail-arch/unicode-ml/Archives-Old/UML023/0481.html|access-date=2021-06-05|website=unicode.org}}

LaTeX markup uses \quad for an em quad, and has other related whitespace escape sequences.[https://www.overleaf.com/learn/latex/Spacing_in_math_mode Spacing in math mode]

History

In 1683, in Joseph Moxon's book on the art of printing, the terms m and n quadrat are attested:{{cite book |last1=Moxon |first1=Joseph |author-link=Joseph Moxon |title=Mechanick exercises: Or, the Doctrine of handy-works. Applied to the art of printing |date=1683 |publisher=Printed for Joseph Moxon on the west-side of Fleet-ditch, at the sign of Atlas. |location=London |page=[https://archive.org/details/mechanickexercis00moxo_0/page/99 99] |url=https://archive.org/details/mechanickexercis00moxo_0}}{{cite web |last1=Blokland |first1=Frank E. |title=em and en Squares |url=https://www.lettermodel.org/em-en_squares.html |website=www.lettermodel.org |access-date=2022-10-28 |ref=blokland}}

And as there is three Heighths or Sizes to be considered in Letters Cut to the same Body, so is there three Sizes to be considered, with respect to the Thicknesses of all these Letters, when the Punches are to be Forged: For some are m thick; by m thick is meant m Quadrat thick, which is just so thick as the Body is high: Some are n thick; that is to say, n Quadrat thick, {{Abbr|viz.|videlicet, 'namely'}} half so thick as the Body is high: And some are Space thick; that is, one quarter so thick as the Body is high; though [...] we shall call these Spaces, Thick Spaces.{{efn|A quarter of an m quadrat is known as middle space today. The term thick space was later commonly used for a third of an m quadrat.}}

In 1771, in the first edition of the Encyclopædia Britannica, it says:{{cite book |title=Encyclopædia Britannica, or, A dictionary of arts and sciences: compiled upon a new plan |date=1771 |publisher=Printed for A. Bell and C. MacFarquhar |location=Edinburgh |page=[https://babel.hathitrust.org/cgi/pt?id=uc1.31210012633382&view=1up&seq=600&q1=quadrat 520] |hdl=2027/uc1.31210012633382 |url=https://hdl.handle.net/2027/uc1.31210012633382}}{{efn|This is worded very similarly to the Cyclopædia of 1728, page [https://search.library.wisc.edu/digital/A4C5AV6Q7LZ5DY8E/full/AVMSIZNGPEUBAN8Y 926].}}

{{Smallcaps|Quadrat}}, in printing, a piece of metal cast like the letters, to fill up the void spaces between words, etc. There are quadrats of different sizes, as m-quadrats, n-quadrats, etc., which are, respectively, of the dimensions of these letters.

In 1841, in William Savage's A Dictionary of the Art of Printing, the terms em and en quadrat are attested:{{cite book

|last=Savage

|first=William

|author-link=William Savage (printer)

|title=A Dictionary of the Art of Printing

|date=1841

|page=[https://babel.hathitrust.org/cgi/pt?id=uc1.31378008169073&view=1up&seq=682 670]

|hdl=2027/uc1.31378008169073

|url=https://hdl.handle.net/2027/uc1.31378008169073

}}

QUADRATS. Pieces of type metal, of the depth of the body of the respective sizes to which they are cast, and lower than types, so as to leave a blank space on the paper, when printed, where they are placed: an en quadrat is half as thick as its depth; an em quadrat is equal in thickness and depth, and, being square on its surface, is the true quadrat, from quadratus, squared; a two em quadrat is twice the thickness of its depth; a three em three times; and a four em four times, as their names specify. Four ems are the largest quadrats that are cast. They are used to fill out short lines; to form white lines; and to justify letters, figures, &c., in any part of a line or page.

In 1903, in Chambers Dictionary, the term quad is attested:{{cite book |editor-last=Davidson |editor-first=Thomas |title=Chambers's Twentieth Century Dictionary of the English Language |date=1903 |publisher=W. & R. Chambers |location=Edinburgh |pages=[https://archive.org/details/chambersstwentie00daviiala/page/752 752]–[https://archive.org/details/chambersstwentie00daviiala/page/753 753] |url=https://archive.org/details/chambersstwentie00daviiala}}

Quad, kwod, {{abbr|n.|noun}} ({{abbr|print.|printing}}) an abbreviation of quadrat.—{{abbr|v.t.|verb transitive}} to fill with quadrats.

[...]

Quadrat, kwod′rat, {{abbr|n.|noun}} a piece of type-metal lower than the letters, used in spacing between words and filling out blank lines (commonly Quad)—distinguished as en {{nowrap|(Image:Chambers_1908_Quadrat_En.png)}}, em {{nowrap|(Image:Chambers_1908_Quadrat_Em.png)}}, two-em {{nowrap|(Image:Chambers_1908_Quadrat_2Em.png)}}, and three-em {{nowrap|(Image:Chambers_1908_Quadrat_3Em.png)}}.

Notes

References