"Besides these properties and proportions of his mould-board, the said Jethro Wood now explains other properties which it possesses, and by which it may be and is distinguished from every other invented thing. The peculiar curve has been compared to that of the screw auger; and it has been likened to the prow of a ship. Neither of these similitudes conveys the fair and proper notion of the invention. "The mould-board, which the said Jethro Wood claims as his own, and which is the result of profound reflection and of numberless experiments, is a sort of plano-curvilinear surface, as herein-before stated, having the following bearings and relations: A right line, drawn by a chalked string or cord, or by a straight rule, diagonally or obliquely upwards and backwards from a point two inches and a half inch above the tip or extremity of the mould-board to the angle where the third and fourth sides of the mould-board join, touches the surface the whole distance, in an even and uniform application, and leaves no sinking, depression, hole, cavity, rising, lump, or protuberance, in any part of the distance. So, at a distance half way between the diagonal line just described, and the angle between the first and second sides, a line drawn parallel to the diagonal line already mentioned will receive the chalked string or cord, or the straight rule, as on an uniform and even surface without the smallest bend, sinuosity, or bunch, whereby earth might adhere to the mould-board, and impede the motion and progress of the Plough, under, through and along the soil. "In like manner, if a point be taken one inch behind the angle connecting the second and third sides, and a perpendicular be raised upon it, that perpendicular will coincide with the vertical portion of the mould-board in that place; or, in other words, if a plumb line be let fall so as to reach a point one inch behind the last mentioned angle, then such a plumb line will hang parallel with the mould-board the whole way; the line of the mould-board there, neither projecting nor receding but being both a right line and a perpendicular line. "Moreover, if a right line be drawn from a point on the just described perpendicular, an inch, or thereabouts, above the upper margin of the fourth side, and from the point to which the said perpendicular, if continued, would reach; if, the said Jethro Wood repeats, a right line be drawn downward and forward, not exactly parallel to the diagonal herein already described, but so diverging from the same that it is one inch more distant or further apart, at its termination on the fifth side of the mould-board, than at its origin or place of beginning; such line, so beginning, continued, and ended, is a right line parallel to the mould-board along its whole course and direction, and the space over which it passes has no inequality, hill, or hollow thereabout.