I had formerly occasion to consider with attention Oliver Evans’s right to a patent for his elevators, conveyers, and hopper boys, and satisfied my self that the elevator and conveyor had been in use some thousand years. of the hopper boy I found no evidence but I was afterwards assured that it had been invented in Maryland and Pensylvania and in use some years before the date of Evans’s patent. he has however in 3 or 4. instances recovered damages in the inferior courts of the US. against persons using them without his licence. the question has never been carried before the Supreme court. the ground of the last decision I am told was that whether he had a right or not under his original patent, Congress had given it to him absolutely by their act in his favor. what damages however are recoverable, I am not able to say, not having the act of Congress here. his corn-crusher stands only on his patent right, and is a gross plagiarism. a smith of the name of Davies in George town made them commonly several years before Evans’s patent, and I have one now in a mill which was in use long before his patent. the only difference is that Daviess’ screw was placed horizontally, & Evans’s vertically. but as to his claims under the special law of Congress, I believe it is safest, however unjust, to acquiesce in them. Accept the assurance of my great respect.

Th: Jefferson