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Source: December 1915 Illustrated World
"The "Ferris Wheel" arrangement shown was adopted in order to give the harvester wheel sufficient bearing surface to hold it up on wet and soggy ground. Such devices were all that enabled gathering much of the year's crop, because of the flooded conditions throughout the country."

1915 was the year of the Galveston Hurricane that flooded much of the Eastern US in August of that year.

This wheel may have been 2 feet wide by 8 feet in diameter. Inside of it was the bull wheel which was rolling and driving all the other moving parts on the harvester.

Link to another large harvester wheel in Canada 1915