A plough possesses five essential features,--a frame or beam to which the horses are attached and which is provided with handles by which the operator guides the plough, a share to sever the bottom of a slice of land--the furrow--from the land beneath, a mould board following the share to turn the furrow over to one side, and a landside, the side opposite the mould board and which presses against the unploughed ground and steadies the plough. To these have been commonly added a device called the coulter, which is a knife or sharp disk fastened to the frame in advance of the share and adapted to cut the sod or soil so that the furrow may be more easily turned, an adjustable gauge wheel secured to the beam in advance of the coulter, and which runs upon the surface of the soil to determine by the distance between the perimeter of the wheel at the bottom and the bottom of the plough share the depth of the furrow, and a clevis, which is an adjustable metal strap attached to the end of the beam to which the draught is secured, and by which the pitch of the beam and the depth and width of the furrow are regulated. The general features, the beam, handles, and share, have existed in ploughs from the earliest ages in history. A plough with a metal share was referred to by the prophecy of Isaiah seven centuries before Christ, “They shall beat their swords into plough-shares;” and such a plough with the coulter and gauge wheel added is found in the Caylus collection of Greek antiquities. The inventions of centuries in ploughs have proceeded along the lines of the elements above enumerated. The leading features of the modern plough with a share and mould board constructed to run in a certain track and turn its furrows one over against the other, appear to have originated in Holland in the 18th century, and from there were made known to England. James Small of Scotland wrote of and made ploughs having a cast-iron mould board and cast and wrought iron shares in 1784-85. In America, about the same time, Thos. Jefferson studied and wrote upon the proper shape to be given to the mould board. Charles Newbold in 1797 took out the first patent in the United States for a plough--all parts cast in one piece of solid iron except the beam and handles. It is a favourite idea with some writers and with more talkers, that when the necessity really arises for an invention the natural inventive genius of man will at once supply it. Nothing was more needed and sought after for thirty centuries among tillers of the soil than a good plough, and what finally supplied it was not necessity alone, but improved brains. Long were the continued efforts, stimulated no doubt in part by necessity, but stimulated also by other motives, to which allusion has already been made, and among which are the love of progress, the hope of gain, and legislative protection in the possession of inventive property.