Several times people have asked me, “How did John Bidwell know how far they had traveled each day? How did they measure the miles?” It’s a good question and I can only guess at the answer, but here goes—
Attempts to measure distance traveled go back a long way. The ancient Romans did it. So did the Chinese. A simple way to measure distance is to tie a rag or ribbon to a wheel and have somebody count the number of revolutions. Multiply that by the circumference of the wheel and you have the distance traveled.
That is not a job I would want, but Julius Caesar would have made a soldier or a slave do the counting.
Benjamin Franklin (of course! who else?) invented an odometer when he was postmaster general in order to calculate the distance between major cities. According to How Stuff Works, it was a geared device that clicked over a mile for every 400 revolutions of the wheel of his carriage. The Franklin Institute has such an odometer in its collection.
William Clayton, a convert to the Church of Jesus Christ of Latter-Day Saints and a Mormon pioneer, developed an improved odometer, which he called a roadometer, in 1847. According the the National Park Service,
Just 10 days and 75 miles out of Winter Quarters, William Clayton recorded in his journal: I walked this afternoon in company with Orson Pratt and suggested to him the idea of fixing a set of wooden cog wheels to the hub of a wagon wheel in such order as to tell the exact number of miles we travel each day. He seemed to agree with me that it could be easily done at a trifling expense. In this fashion the odometer, called the roadometer, was invented in 1847 by the Mormon pioneers crossing the plains from Missouri.
The National Park service article on Clayton’s odometer has a diagram, in case you want to build your own. The use of this device enabled Clayton to give accurate information to future emigrants in his The Latter-day Saints’ Emigrants’ Guide.
But Clayton made his device in 1847, and Bidwell was on the trail in 1841. Did he and his companions have some kind of odometer, or were they estimating? That’s the question.
Bidwell never mentions having an odometer, and neither do any of the other members of the party. At least three members of the Bidwell-Bartleson Party kept daily journals: Bidwell, James John, and Nicholas Dawson. It is interesting to note that their records of mileage do not always agree. For instance, on July 4th, Bidwell writes that they traveled 22 miles. Jimmy John has 16 miles, and “Cheyenne” Dawson has 20.
I suspect they were estimating the distance, based on hours of travel, the speed (very slow) of oxen, the nature of the terrain, etc.
If I ever get a chance to meet John Bidwell, I’ll ask him that question!