The H&Co Institute for Unapplied Mathematics

Typefaces: Gotham Narrow Book, Archer Book, Indicia, Dividend, Gotham Extra Narrow Medium, Bayside

We’ve received our share of intriguing questions over the years, but this one takes the cake. On Monday, a correspondent called from National Public Radio to discuss the implications of typesetting a number with twelve million digits.

The number in question is 243112609-1, which holds the title for World’s Largest Known Prime Number. Mathematicians have known since at least the third century BC that for many values of n, the formula 2n-1 produces a prime number. When it does, the result Mn is called a Mersenne Prime, after the seventeenth century French mathematician who calculated the first 257 of them by hand — quite something when you realize that M257 has 78 digits. (And, so very cruelly, it’s not prime.) The search for prime numbers, an esoteric pursuit that rivals typeface design for its cultishness, has continued ever since; these days it’s assisted by the Great Internet Mersenne Prime Search, a project that organizes the downtime of almost 90,000 volunteers’ computers into a collective effort to find the next great prime.


Spotting the Long-Necked Kern

This publicity photo, from the Berthold foundry’s Specimen No. 525B (late 1950s?) shows the foundry type for Arabic Shaded No. 50. In addition to demonstrating the maker’s facility with both non-Latin scripts and elaborate ornamentation (this is an outline face with a drop shadow, produced at 30pt), this diagram shows an interesting technique for kerning Arabic’s many delicate features.

A kern, in the literal sense, is any part of a character that extends beyond the body. The more delicate a kern, the more likely it is to break off during use, and Arabic is among the world’s most sinewy scripts. To compensate, this typeface was cast with an especially long neck — the distance from the top-most printing surface (the face) to the non-printing surface below (the shoulder) — so that kerns would be stronger, and more fully supported by adjacent characters. A clever, simple solution.

Pop quiz: Arabic reads from right to left, and printing type is always reversed. Which end is the start of the line? If you’re disoriented, imagine the sixteenth century French and Flemish typefounders who produced some of the world’s finest Arabic typefaces, three hundred years before the invention of the mass-produced silvered-glass mirror. —JH

Adventures in Kerning, Part II

Typeface: Verlag Book

A kerning table, which makes special allowances for characters that don’t fit together naturally, can reveal a lot about the personality of its designer. Every font pays special attention to the pair Va, but the font that includes Vr suggests a familiarity with French (vraie) or Dutch (vrouw). Pairs like Wn or Tx hint at an even broader perspective (Wnetrzne, Poland; Txipepovava, Angola), and the designer who kerns the ¥4 has presumably spent some time thinking about finance. Including ÅÇ is the mark of someone who’s trying too hard: these letters don’t nest together naturally, but nor do they appear together in any language.

When I first learned about kerning, mystifying to me was the presence of Yq in almost every one of Adobe’s fonts. Adobe’s early faces sometimes neglected far more common pairs, or even whole ranges of the character set — many fonts didn’t kern periods, dashes, or quotation marks — but Yq was ever-present. When I met him in the early nineties, Adobe’s Fred Brady hinted at why: located in northern California, Adobe’s designers often had a thing for viniculture, and one of the world’s most famous dessert wines is produced by Château D’Yquem.

We’ve included Yq as a standard kerning pair ever since, though I’d never gotten to see it in action until yesterday. Here, in the window of Sotheby’s on Bond Street, is our Verlag typeface, Yq kern and all. There are kerns obscurer still that we’re waiting to see in public, though I don’t suppose I’ll be seeing the 9th century Old English word wihxð (wax) in the window of Sotheby’s anytime soon. —JH

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