1952: Frank Zybach gets a patent for the center-pivot irrigator. Hundreds of thousands of crop circles will appear on landscapes around the world ... eventually.

You've seen 'em if you've flown across farmland in the United States or other nations: big green circles of irrigated land, making repeated dot patterns. But they weren't always there.

Zybach grew up in Nebraska but was farming in Colorado in 1947 when he saw a demonstration of modern movable irrigation. Workers were moving and connecting pipes fitted with sprinkler heads from one part of a field to another. Sprinklers could beat a couple of problems: uneven, hilly terrain and the tendency of water to run into sandy ground before getting to the end of the ditch.

But Zybach, a lifelong tinkerer, saw something more: Why have humans set up, take down, move the equipment and repeat? Why not have the equipment move itself?

Zybach built his first prototype within a year. It rotated around a center wellhead. Guy wires that were attached to support towers held the sprinkler-fitted water pipes above the ground. Control wires and two-way water valves kept the towers in line. The first support towers moved on skids, but Zybach soon replaced those with wheels propelled by the irrigation water itself.

He applied for a patent for the "Zybach Self-Propelled Sprinkling Apparatus" in July 1949. He knew he needed to improve his invention -- making it tall enough to work for corn, among other things. So, the same year he got his patent, he moved back to Nebraska and went into business with a friend, A. E. Trowbridge.

The duo didn't immediately succeed, partly because Zybach kept making improvements before Trowbridge could sell the models they'd already manufactured. They sold the patent rights for a 5-percent royalty to farm-equipment manufacturer Robert Daugherty of Valley Manufacturing (later Valmont) in 1954.

Valley built only seven systems the following year, but it kept on improving the device. Variable pressure let farmers apply different amounts of water on each full rotation. They could apply fertilizer and pesticides automatically, too. End guns let water reach those dry corners between the circles. Business took off in the 1960s. The amount of land tended by one irrigation worker quadrupled from about 400 acres to 1,600 acres.

More than a quarter-million center-pivot irrigation systems now water fields around the world. Modern systems run in forward or reverse on rubber wheels driven by electric motors. The control sensors that keep the support towers in line have evolved from simple mechanical linkages to computerized sensors. Some systems use GPS and wireless to control water flow. They take directions from laptops and cellphones. Sophisticated mechanical trusses, not wires, support the pipes.

But what about those empty corners between the circles? Some countries now arrange their circular fields in large, hexagonal patterns to minimize the unsprinkled areas. That's hardly practical in the United States and elsewhere where land holdings have already been divided up in big, old-fashioned squares. So, the up-to-date center-pivot systems rely on low-voltage, radio-signal wires buried in the corners of the field. A sensor at the end of the pivot arm picks up the signal and telescopes the pipe outward toward the corner, then retracts again, following the border of the field.

And, as that technology spreads, the circles you see from your jet-plane window seat may someday be a thing of the past.

Source: Wessels Living History Farm

SAN FRANCISCO – More than 100 zine-makers packed the County Fair building in Golden Gate Park over the weekend to celebrate San Francisco's annual Zine Festival.

The two-day conference featured a wide variety of DIY arts and crafts, zines, comics and a gypsy-like atmosphere. Attending noobs were also treated to hands-on workshops, from bookbinding to illustration and Q & A sessions with accomplished self-publishers.

For zinesters, zines are like the blogs of the print world. They're an essential part of offline geek and underground culture and their DIY aesthetic has influenced an entire generation of designers and writers.

Click through the gallery for highlights from this DIY ComicCon.

Left: Festival-goers browse through the plethora of independently published zines and books.

Jonathan Fetter-Vorm, one half of the production company Two Fine Chaps, displays an array of his self-published work. His work ranges from a large, full-color illustrated book of the poem Beowulf to a very small, hand-made, three-dimensional pop-up fable titled The Clockmaker's Joy.

"I wanted to make books that are fun to hold, interesting to read and beautiful to look at," Fetter-Vorm said.

Rani Goel's Typecritters zines feature letter art made from mirroring and layering type. Her booth also displays her Servings zine, which tackles the issue of body image and our cultural obsession with weight and food.

"There's something about someone's handwriting, something more real about it than a MySpace or a blog, something raw," Goel said. "And there's room to be messy, it doesn't have to be perfect."

Jennie Hinchcliff (left) and Carolee Gilligan Wheeler, of Pod Post, model their zine merit badges.

"We wanted the merit badges to be about something we care about," Hinchcliff said. "Merit badges for book and zine making." "Instead of cookie selling," Wheeler adds.

Amy Martin, a cartoonist, gets a little work done at her booth and perhaps a head start for next year's festival.

"Last year was the first [festival] I did," Martin said. "The shows are great and you get to meet lots of people."

Matt DeLight, illustrator and co-producer of several comics, described his work as autobiographical, funny and tragic.

"It started with a love of comics as a kid," DeLight said. He stumbled upon an issue of Too Much Coffee at 16 that detailed how to make your own mini comic. "It blew my mind to think that I could go to Kinko's and make my own comic."

The 2008 SF Zine Festival moved to the SF County Fair building in Golden Gate park this year in anticipation of more exhibitors and a larger crowd than ever -- twice the size of last year's.

Kelly Lee Barretts (right) mans her street-photography mini-book booth with Jon LaSalle (middle).

"I had taken a bunch of photos and was rolling around with them on the floor of my room one night and decided to make a book out of it," said Barretts, a UC Santa Cruz graduate. Barretts has books available in three different sizes, from the miniscule to the pocket-size.

Lori Stein (left), author of Ranger Strange Bunny, shares table space with professional Yo-Yoer and ziner, Doctor Popular.

Doctor Popular peddled his zines, hand-made iPhone cases and yo-yos. "Three things keep me alive: yo-yoing, crafts and tailoring," Popular said. "Some of that is represented here."