On Agrlcidtiiral Mechanics. 1*21 



distance between the paths of the teeth through the ground. Kirkwood, 

 however, abandoned Finlayson's form of the toothy and substituted one 

 such as that represented in page 123 ; and in his machine the first fault 

 of Finlayson's grubber remains in full force, — the frame-work is too near 

 the ground. 



Biddell's scarifier is another implement of this class, much stronger 

 and more clumsy : the frame-work* is similar in form to Finlayson's, the 

 teeth as before being arranged in two rows right across the direction of 

 the path of the machine. It is supported on two large wheels behind, 

 and two small ones in front, by which it is raised 20 inches oft" the 

 ground, much higher than in Finlayson's. There is, above the machine, 

 a complicated apparatus for lifting it out of the ground. The front 

 part is raised by one lever, and the hinder part by another. The form 

 of the tnoth has nothing to recommend it : it is necessarily strong and is 

 attached to the frame-work by bolts : to this tooth either a chisel- edge or 

 a duck-foot may be attached ; the one being intended to stir the ground 

 merely, and the other to pare its surface. This machine, from its height 

 oft" the ground and its great strength, is well calculated to work very 

 rough and conchy land. If, however, the ground is damp when the 

 paring-teeth are used, it is impossible to work it, as it immediately clogs. 

 The whole of the machine is of cast-iron, and the teeth are therefore 

 liable to break in stony ground. Four horses are required to work this 

 machine; it is made nine teeth wide = 4 feet 6 inches j five teeth in 

 the back row and four in the front. 



Another implement, a very great improvement on Finlayson's harrow, 

 has been put forth by Scoular of Haddington, who supplies them there 

 at 7/. each. The form of the frame-work, the form of the teeth, the 

 arrangement of the teeth, and the height of the frame-work, ar ehowever 

 the same, still faulty. The improvement consists in a simple means of 

 raising or lowering the frame-work altogether, and of keeping it at any 

 one depth. It will be understood from the annexed figures, which give 

 a side-view and a ground -plan. It is much simpler than Kirkwood's, 

 and possesses, by means of the notched upright, a very simple method 

 of keeping the machine at one depth ; the lever or handle by which it is 

 raised is merely fixed in one of these notches : this is effected in Kirk- 

 wood's grubber in a complicated manner. Finlayson's, Kirkwood's, 

 and Scoular's are wholly wrought-iron, except, of course, the wheels. 

 Now taking Scoular's as the best of the four for general purposes — and 

 here I may say, that having only five teeth, and working a width of 

 3 feet, it is perfectly manageable by two horses — if we first take Scoular's 

 machine and point out all its faults, we shall see how these have been 

 remedied in a machine, the invention of the managers of Lord Ducie's 

 Iron- Works at Uley, in Gloucestershire. 



1st. The wheels are too small; the frame- work is greatly too near to 

 the ground. 



2nd. The teeth, being in two rows right across the path of the 

 machine, are only twice the distance from one another that exists be- 

 tween any two adjacent paths or ruts made by them in the ground, 



* See Journal, vol. i., p. 357. 



