122 



Gn jiijn' cultural Mechanics. 



3rd. The teeth being in two rows, there is necessarily a tendency in 

 the bars to which they are fixed to twist, for theie is not the strain of 

 one only, but of three teeth, all acting on one bar, tending to twist it. 



4th. The teeth, though of a good form with regard to their general 

 figure, are not good, if we judge of their strength by their section. This 

 is broader than it is thick ; whereas, to stand the great strain placed on 

 them when at work, it should be much thicker than wide. This fault 

 occasions, when the machine is at work, an almost constant recurrence 

 to the smith's shop, the teeth becoming bent. 



5th. The whole machine, being of wrought-iron, is expensive, 



6th. Although the mode in whicli the implement is raised out of the 

 ground answers the purpose perfectly, and is beautifully simple, yet it 

 is difficult to manage. It is as much as a man can do to lift it out of 

 the ground at the end of the field, when it is at work. And the difficulty 

 is due in part to this circumstance : it will be observed that the cranks 

 by which the hind wheels and front wheels are attached to the machine 

 all lie behind their points of attachment, — they incline from the horses. 

 Now, in consequence of this, in raising the machine, it is evidently by 

 the action of the lever pulled towards the driver — pulled backwards, 

 and thus in lifting it out of the ground the man has not only the mere 

 weight of the im])lement to lift, but he has to overcome the whole force 

 of the horses which pull it forward, and thus tend to keep it in the 

 ground. These points, then, require alteration, and at the same. time 

 an implement was required which should be as efficient and as easily 

 drawn. 



With regard to the first point, the Uley Cultivator rests on four 

 wheels; the front ones being 18 inches in diameter, and the hind ones 

 3 feet 4 inches in diameter. From the front ones rises an iron rod, having 

 a circular section which passes through the point or nose of the frame- 

 work ; the hindmost ones rest on cranks on an axle which runs straight 

 through the frame-work : the frame-work is thus 20 inches off the ground. 



2nd. The teeth are not placed in rows, but are arranged as in the 

 annexed figure (p. 16), and somewhat similar to the arrangement in 



[Lord Ducie's Cultivator.] 



Kirkwood's grubber. The space between each is thus 2 feet — tvvic: 

 that of Secular's — while the distance between the paths of each is only 



