Before electronic scales weighed the grain, weights and a fulcrum did the trick.
Story by Kristen Cart
Nothing is quite so revealing as a vintage book. Ronald Ahrens alerted me to his discovery of an engineering textbook, written by Milo S. Ketchum, about retaining walls and elevator bins. Prof. Ketchum was the dean of the College of Engineering at the University of Colorado (my alma mater) when he wrote The Design of Walls, Bins, and Grain Elevators. First published in 1907 by the Engineering News Publishing Company, of New York, it boasted a second edition in 1911.
From the first few paragraphs, revelations abound. Most eye-opening is the historical context of its publication.
In 1907, surviving Civil War veterans were well-established in their old age. No one yet considered the possibility of the worldwide conflagrations to come. Comanche wars in Texas were still an ugly living memory, more recent to people than the Vietnam War is to us. Grandmothers shared their memories of living in sod houses on the Great Plains. Movies were not yet a national pastime. Airplanes and automobiles were on the drawing board–the Ford Model T would begin production the following year.
When grain was delivered to elevators, it came by barge, rail, or wagon. The business model that drove the elevator boom was in its infancy. Engineers had just begun working with reinforced concrete for bridges, dams, and skyscrapers, but much remained to be done.
In the introduction, the book gets right to the nuts and bolts of the problem it purports to solve.
A special subset of engineering concerns granular fluids. Grain acts both as a solid and as a fluid–it can be piled in a conical pile because of internal friction which is absent in liquids, but it can flow very much like water. Containing such a fluid requires an understanding of internal pressures–both vertical and outward–that are exerted on a container. All of these considerations boil down to a mathematical model that accurately describes the materials, structures, and shapes required.
The book first examines retaining walls, the simplest structure for containing granular fluids, and proceeds to bins and elevators from there.
Thus we have a textbook that gets into the weeds of that math and physics, ultimately used to teach future designers how to do grain bins. The young men schooled in the years following 1907 would be the builders, engineers, superintendents, and architects who started the concrete elevator building boom.