PROVO — A legend about the man who kept records in the first Mormon pioneer company says William Clayton was such a stickler for detail that he tied a red bandanna to a wagon wheel and painstakingly counted how many times it went around to measure the trek's progress.

William Clayton clearly was a fussbudget about pioneer mileage in 1847, but a guide with his measurements of the Mormon Trail was published in St. Louis in 1848 and became invaluable to pioneers and to the 49ers of the California Gold Rush.

There's no evidence Clayton ever used a red bandanna, but he was the one who persuaded Brigham Young to form the team that engineered an ingenious wagon-wheel odometer. The original pioneer odometer has been lost to history, but Brigham Young University mechanical engineering professor Larry Howell has created the first working replica of the remarkable device.

"Other people have built replicas," Howell said, "but none have been to the actual dimensions. One of the myths about the odometer was that the dimensions were unknown."

Howell dug through the journals of Clayton and Orson Pratt and said that with those first-hand descriptions of the wooden gadget and his own knowledge of gear design — he teaches a gear design class at BYU — he realized an exact replica was possible.

Howell usually pushes the envelope of modern mechanical engineering, working on things such as microprocessors and fitting working mechanical devices on microchips. But he was intrigued when he learned about the odometer.

He'd seen an old odometer at the Museum of Church History and Art of The Church of Jesus Christ of Latter-day Saints in Salt Lake City that was proclaimed in church history books to be the one built by Clayton, Pratt and a craftsman named Appleton Harmon. At first, Howell thought he'd try to add to a book called "Landmarks in Mechanical Engineering."

Then he learned that former BYU professor Norm Wright had proved the museum piece wasn't the Young-Clayton-Pratt odometer — and that no replica with the right dimensions existed.

"I've been a nerd for a long time," Howell said, "but the novelty of these guys conducting a research-and-development project in the wilderness really intrigued me."

The red bandana story could be true. As the pioneers moved across Iowa after the Mormons were ejected from Nauvoo, Ill., Clayton became frustrated that his estimates of daily pioneer progress were regularly lower than those posited by others.

"He doesn't say it like this," Howell said, "but it's clear he's getting some grief for his lower estimates."