When plowing on a slope, unless one could go around and around the hill, part of the time the ground was being turned uphill, and part of the time, downhill. To minimize erosion, downhill turning over the whole field was much preferred. One approach was to build a plow with a moldboard and share that could be flipped from one side of the beam to the other and thus turn the dirt to either the right or the left. Another solution was to have two complete plows, one right-handed and one left-handed, mounted on wheels and arranged so that either plow could be used. In the U.S., such hillside plows were called two-way plows because the plow could go either direction and still throw the dirt the same way. In England, they were called one-way plows because, regardless of the direction of travel, the dirt was only thrown one way.
1001 Words and Phrases You Never Knew You Didn’t Know by W.R. Runyan Copyright © 2011 by W.R. Runyan