116 



COMBINED POETABLE ENGINE 



a small windlass, which, by unwinding, allows the pulley to 

 be drawn towards the engine. The subsoiler only worked in 

 one direction, a horse drawing it back with a cable 274 yards 

 long. Seven and one-half acres could be ploughed without 

 shifting the engine. Gustave Scribe wished to apply this 

 system to the polders of Zealand, where stiff soils 4 feet in 

 depth are only ploughed to a depth of 9^ inches. 



The winding drums in actual use (Vernette, Guyot, 

 Amouroux) generally rotate vertically, when the plough is 

 to be hauled back by a horse. Figs. 76 and 77 represent Ver- 

 nette's winding drum mounted on wheels for travelling on 



roads. In work, the wheels are removed, and the machine fixed 

 on the ground. A belt connects the pulley of the engine to that 

 of the winding drum. Different gearing systems may be inter- 

 posed between the pulley and the drum to modify the speed.* 



* In the old model, the transmission of the shaft of the pulley to that of 

 the drum was made by means of a spiral gearing. This system was applied 

 by Gru in 1891. 



