When the February issue of Wired Magazine debuted with a new logo, we explained inside the magazine that it “obeys the Law of Optical Volumes.” We were being coy –many readers went scurrying to Wikipedia and Google to investigate this curious law, only to find … nothing.

Here’s the skinny: The Law of Optical Volumes is Wired creative director Scott Dadich’s term for a typography rule that governs the spacing of characters within a font. The theory behind it has been evident on newsstands for years now, thanks in part to typography guru Jonathan Hoefler, whose firm Hoefler & Frere-Jones designed Wired’s new typefaces used throughout the magazine. You can also see Hoefler’s work at typography.com – or in The Wall Street Journal, Esquire and Martha Stewart Living.

And here’s a definition: The Law of Optical Volumes states that the area between any two letters in a word must be of equal measure throughout the word, and remain consistent throughout the body of text.

The Law boils down to the science of kerning. In typography jargon, kerning is the act of adjusting the space between two letters to make words and sentences lay out more evenly. For example in the word “VAST,” there is usually reduced space between the V and A, and maybe extra space between the S and T. Otherwise the “VA” would seem too far apart and the “ST” would seem cramped.

The formal definition for a font includes not only the shape of each letter, but also a series of *kerning pairs *that specify a customized distance between certain pairs of letters, such as the “Yo” in “You.” Without the adjusted spacing, these pairs appear too far apart or too close together.

Typographers strive to balance letters so that the area of space between each pair of letters is identical. The premise is that human eyes unwittingly measure that area to decide how far apart each pair is. If Scott were more of a geometry wonk, he’d have dubbed it the Law of Optical Areas rather than volumes, but that doesn’t sound as imposing.

Traditional fonts usually included several hundred kerning pairs. Hoefler & Frere-Jones’ fonts are super-fussy - they can include 10,000 pairs to get every combo of letters exactly right. In the font example shown below, notice how the size of the yellow area between each pair of letters in the word “colophon” is adjusted to be the same.

The same goes for Wired’s new logo. It alternates between letters without and with serifs, yet the area between each pair of letters is about the same, thanks to the serifs on the I and E and lack thereof on the W, R and D. This equivalence makes the logo easier to see and read across a crowded supermarket aisle. The alternating fonts also make the letters seem to blink on and off as you read them from left to right, in emulation of digital ones and zeroes.

Unfortunately this advanced, scientific approach to font layout is still only available in ink on paper. Web fonts in 2007 still don’t have kerning pairs. We don’t know why. To see and appreciate the Law in action beyond our logo, you’ll need to pick up a copy of the magazine. UPDATE: I'm completely wrong! See the comments below for Web-based solutions.