Capturing the Knowledge of Mill-Wrights

Driving through Napa over the weekend, I saw a roadsign that said “Milling Today” at the Old Bale Grist Mill. I had to stop and take a look. The restored mill has a 36′ “overshot” waterwheel so called because water pours on top of the wheel, directed there by a long “flume” that brings water from a nearby pond. The Bale Mill operated in the late 1840s into the 1860s, spanning a period of time when Napa was part of a Mexican province to its becoming part of the Bear Flag Republic and finally the State of California. This mill was grinding wheat grown in the Napa Valley long before there were any vineyards, and the flour was supplied to miners heading out to the gold fields in 1848.

Overshot Waterwheel.jpg

Inside the mill are two different sets of millstones, one enclosed in a box for safety. A docent demonstrated the operation of the mill, setting the waterwheel in motion, which turned the gears underneath the millstones, and caused the wooden floorboards to rumble. Eventually, as the momentum picked up, the millstones themselves began to spin. Out came a steady flow of wheat flour. The docent said that the phrase “nose to the grindstone” comes from the constant attention required of the miller who has to smell the wheat to check for ozone, which is caused when the two large pieces of quartzstone are rubbing against each other.

Inside the mill

After the demonstration, the docent held out a book published in 1795 called “The Young Mill-wright and Miller’s Guide” by Oliver Evans, an early American user manual for builders, inventors and operators. Check out a scan of fifteenth edition of the guide from 1860 on Google Books.

Oliver Evans was an inventor himself, and Wikipedia says that “his most important invention was an automated grist mill which operated continuously through the use of bulk material handling devices including bucket elevators, conveyor belts, and Archimedean screws.” His book played an important role in the spread of mills in American, explaining the design, construction and operation of mills, even pointing out areas where new inventions were needed. The docent believed the book was used in the construction of the Old Bale Mill, which was probably built by people who had no previous experience building a mill.


The docent showed us the detailed diagrams in the book.

Docent and book.JPG

Then he identified an unusual feature found in the first edition. At the back of the book, there was a section that listed the subscribers for the book, and at the top of list were George Washington and Thomas Jefferson. In those times, to publish a book meant getting readers to commit in advance to buying it. An enterprising publisher/author would try to cover his costs before incurring them. I understood that much about the subscription model. What I didn’t realize was something that the docent pointed out. He said printing a list of subscribers was an early form of a social network — the list identified others who were interested in the same subject and whom you might wish to consult for a variety of reasons. If you were studying Evans’s plans, you might want to correspond with someone else who was doing the same thing. Pretty cool.

The preface to the fifteenth edition of Evans’s book says this about his fame and fortune:

The improvements in the flour mill, like the invention of the cotton gin, apply to one of the great staples of our country; and although nearly forty years have elapsed since Mr. Evans first made his improvements known to the world in the present work, the general superiority of American mills to those even of Great Britain, is still a subject of remark by intelligent travellers. Mr. Evans, however, experienced the fate of most other meritorious inventors; the combined powers of prejudice and of interest deprived him of all benefit from his labours, and, like Whitney, he was compelled to depend upon other pursuits for the means of establishing himself in the world. His reward, as an inventor, was a long-continued course of ruinous litigation, and the eventual success of the powerful phalanx which was in league against him.

Still, I think about how this old user manual and this old mill have endured.