The minor problem which now remained of freeing the cylinder's teeth from their congestion of lint found a solution in Mrs.Greene's stroke with a hearth-broom.

Whitney, seizing the principle, equipped his machine with a second cylinder studded with brushes, set parallel to the first but revolving in an opposite direction and at a greater speed.

This would sweep the teeth clean as fast as they emerged lint-laden from the hopper.

Thus was the famous cotton-gin devised.[14] [Footnote 12: Letter of Phineas Miller to the Comptroller of South Carolina, in the _American Historical Review_, III, 115.] [Footnote 13: M.B.Hammond, _The Cotton Industry_ (New York, 1807), p.

23.] [Footnote 14: Denison Olmstead, _Memoir of Eli Whitney, Esq_.