414 



SCIENCE OF AGRICULTURE. 



Part II. 



350 



diagonals, and for resisting the lateral or shaking motion occasioned by encountering 

 obstacles. ( Quart. Jour. Agr. vol. ii. p. 555. ) The principal parts of harrows are 

 generally made of wood ; but they are frequently also constructed entirely of iron. 



2697. The Bervdckshire harrow {fig. 350.) is the most perfect implement of the kind in 



general use. It consists of two parts joined to- 

 gether by iron rods, having hasps and hooks. 

 Each part consists of four bars of wood technically 

 termed bulls, and connected together by an equal 

 number of cross bars of smaller dimensions mor- 

 tised through them. The former of these bars 

 may be 2^ inches in width by 3 inches in depth, 

 and the latter 2 inches in width by 1 inch in depth. 

 The longer bars are inclined at a certain angle to the 

 smaller, so as to form the figure of a rhomboid, and 

 they have inserted into them the teeth at equal dis- 

 tances from each other. This inclination of the 

 longer bars is made to be such, that perpendicu- 

 lars from each of the teeth, falling upon a line 



drawn at right angles to the line of the harrow's motion, shall divide the space between each 

 bar into equal parts; so that the various teeth, when the instrument is moved forward, shall 

 equally indent the surface of the ground over which they pass. {Quart. Jour. Agr.) 



2698. The angular-sided hinged harrow {fig. 351.) is one of the best implements of 

 351 ^ 



the kind, as it both operates on the groimd with great regularity, and is less liable to 

 ride or be deranged in turning, than the common, or the rhomboidal harrow. 



2699. The grass seed rhomboidal harrow {fig. 352.), is nothing more than the Ber- 

 wickshire harrow on a smaller scale. It is used chiefly for harrowing in clover and 

 grass seeds when sown among corn crops, or even alone. 

 352 



353 



2700. The common bralce {fig. 353.) is merely a harrow of the common kind, of 



