MECHANICS AND USEFUL ARTS. 37 



are operated by cranks. Above and below the .cog-wheels, on each 

 side, are sectors, whose general shape is triangular, the apices of the 

 upper ones being turned upwards, and those of the lower downwards. 

 The axle of the lower cam rests upon the curved surfaces of the lower 

 sectors, while that of the upper one presses on the curves of the upper 

 sectors. The axle of the upper cam moves upwards in its side bear- 

 ings, and the upper sectors are pressed upwards, pushing up a plate, 

 which moves in guide-slots in the erect frame, so as to press any thing 

 placed on it against some rebutting back. The upper sectors move in 

 one direction, while the lower ones move in the contrary direction, 

 bringing their curves to act most effectually, balancing all the mo- 

 tions, and acting in right lines through points of contact, produced by 

 the contact of the curved surfaces of the axles, cams, and sectors; con- 

 sequently the amount of friction is very small. These presses have 

 been very extensively introduced, and are highly spoken of. 



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STEAM-PLOUGH. 



MR. JAMES USHER described to the British Association, at Edin- 

 burgh, a steam-plough of his invention. He says that all former at- 

 tempts at ploughing by steam have gone on the principle that ploughs 

 must be dragged through the earth, whereas a moment's consideration 

 will show that the ploughshare and its bearer are exactly similar to a 

 common anchor, which, if thrown into the sea, will hold even the 

 largest vessel. To obviate this difficulty, in the present machine the 

 plough is reversed, and made like an anchor, thrown out before a ship, 

 by which the vessel is hauled forward ; or, in other words, the plough 

 is inside a paddle-wheel, instead of an anchor cast astern, and thus the 

 carriage is propelled along the land. To obviate the objection that 

 five or six ploughs entering the earth at the same time would lift a 

 solid piece of earth and carry it round, though all the ploughs are put 

 on the same axis, they are so arranged that no two shares come into 

 action at the same moment. On applying the power of the steam- 

 engine to the ploughs, it was found that they ran along the earth with- 

 out turning it over, and it became necessary to affix a drag to the 

 wheels, which was done by connecting the wheels of the carriage with 

 the wheel \vhich drives the ploughs, so that a uniform stroke is ob- 

 tained for each plough, and it cannot proceed till it has turned over 

 the desired area. By this it will be seen that the ploughs drive the 

 carriage-wheels at the necessary reduced speed, the forward motion 

 of the machine being communicated from the plough to the carriage, 

 instead of from the carriage-wheels to the ploughs. The machinery 

 used consists, generally, of a locomotive boiler and engine, placed in 

 a frame above the wheels, the weight being so disposed as to be princi- 

 pally over the hind wheels. The fore wheels are fitted to a revolving 

 frame, similar to an ordinary road carriage, to be turned round in a 

 small compass. The ploughs can be elevated or depressed for deep or 

 shallow ploughing. Civil Engineer and Architect's Journal, Oct. 



LORD WILLOUGHBY D'ERESBY has published a pamphlet describing 

 another steam-plough, which consists of a locomotive engine, weigh- 



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