124 On J (jrkultnral Mechanics. 



to the frame. In this, however, instead of inclining backwards, and thus 

 requiring, on lifting the machine, an exertion of force, as we before ex- 

 plained, against the whole pull of the horses, the crank is thrown for- 

 ward in exactly the other way; and thus the whole force of the horses, 

 instead of being exerted against the effort of the driver to raise the 

 implement out of the ground, is actually exerted in assi^ting him to 

 do so. 



The front part of the machine is not raised in the same way as the 

 hinder part, by a crank on the front wheel, but it slips up and down the 

 vertical pole attached to them, and is raised in the following way : the 

 cranks of the hinder wheels are attached to an axle, which passes 

 through the frame, and thus supports it. On this axle a toothed wheel 

 is fixed : this toothed wheel is worked by an endless screw on a shaft, 

 which also works in the frame of the machine. This shaft working by 

 means of this endless screw, a toothed wheel on the axle across the imple- 

 ment is necessarily parallel to the length of the machine, and is turned 

 by means of a crank- handle above. Turning this handle round in one 

 direction, it is evident that the axle on which the toothed wheel is fixed 

 will be turned round, and the crank of the hind wheels raised, and thus 

 the frame brought nearer the surface of the ground, the teeth let deeper 

 into it; by turning the handle the other way, the hind part of the 

 machine is raised. 



In order to get the front part of the machine raised and lowered ex- 

 actly as the hinder part of it, the following simple method is adopted : 

 on the axle of the hinder wheels a crank is fixed, attached for greater 

 simplicity to the pinion before mentioned. It is the same length as the 

 crank of the hind wheels; when, therefore, the pinion is turned round, 

 these wheels being by this crank raised, that is, the frame being lowered, 

 say 2 inches, the extremity of this crank is lowered 4 inches.* From the 

 crank a vertical rod rises, which is attached to one end of a lever rest- 

 ing at the other end on the vertical rod at the front of the machine, and 

 attached exactly at the middle by means of a rod of iron to the frame- 

 work of the implement. When, therefore, the point of the crank is 

 lowered 4 inches, the hindmost extremity of the lever is also lowered 

 4 inches, and, as it rests on the top of the vertical rod at the other end, 

 it depresses the rod in the middle and the frame-work attached to it 

 exactly 2 inches, the same as the hind part of it. The perfect parallelism 

 of its motion is thus ensured, while the mode of lifting it requires but a 

 small exertion of force. The implement is altogether about 6 cwt. in 

 weight. It is supplied at Uley at prices varying according to the size, 

 weight, &c. at which it is ordered, certain forms of the implement being 

 intended for two horses and others for four. Before leaving this subject 

 I wish to say a word which might perhaps have been more properly 

 placed in the account of the plough. 



The looseness in which the use of this implement leaves the land is, 

 in every case, except when dry weather is anticipated, the most advan- 

 tageous for the germination of the seed or the growth of the plant. 



* Two inches by the action of the crank, and other^'2 inches by the 

 lowering of the frame to which the crank is attached. 



