# The History of the Pi Shawl

Since today is Pi Day, I wanted to share a little about the history of the Pi Shawl--a circular shawl with regular increases that can either be worked in the round. A half-Pi shawl is worked flat but the priniciple of increasing is similar. The Pi Shawl is based on the geometry of Pi--a mathematical constant that is the ratio of a circle's circumference to its diameter, or 3.14159265359...

Using the geometry of Pi, the famous Elizabeth Zimmermann invented (or, as she would say, un-vented, as she liked to point out that everything is already known and "unvented" things are the result of our subconsciousness remembering them) the Pi Shawl, which she first discussed in her book, *Knitter's Almanac*. The basic Pi Shawl uses rows of plain knitting interspersed with increase rounds (she favored eyelets--knit one, yarn over), but you can use any type of increase you want. Starting from the center of the shawl, the diameter of the shawl doubles at the same rate as its circumference. That is, increase rounds double the number of stitches on your needles.

The blog Life Beyond the Kitchen provides an example of a basic pi shawl where you begin with 9 stitches, knit a round, then increase every stitch so that you have 18 stitches. Then you knit three rounds before increasing every stitch again. Then you knit six rounds before increasing every stitch, and so forth, doubling the number of plain knit rows between each increased row. The result is a series of circles.

A number of lace designers love Pi and Half-Pi shawls because they are fabulous for "unventing" intricate lace patterns among the increases.

Want to try your hand at making a Pi Shawl? Mwaa Knit designed __this beauty__ in honor of what would have been Elizabeth Zimmermann's 100th birthday.

If you read Sally Goldenbaum's *The Wedding Shawl*, you know that Nell and the other Seaside knitters made Izzy a Pi Shawl that's based on Knitting Harpy's __Shipwreck Shawl__. I made one of these about a decade ago out of some heavenly Dream in Color Smooshy.

Dale Hwang's __Supernova Circular Shawl__ is classified as a "piece of cake" in Ravelry if you are nervous but want to try making a Pi Shawl.

Although it is a paid pattern, Janine Le Cras's __Secret Garden Pi Shawl__ (pictured at the start of this blog) is another fun one. Mine is made using Sweet Sparrow House Wren fingering tweed.

My tip for making a Pi or Half-Pi shawl is to use stitch markers because they will help you remember where you are placing your increases and where your lace section repeats begin and end.

Happy Pi Day!