50 TRENCHING AND SUBSOILING 



To work at a greater speed the endless screw and its cog- 

 wheel may be fixed direct on the drum-shaft. In this case 

 the machine resembles that of Vernette (Fig. 23). For 

 medium depths, if the soil is light and if one has a powerful 

 engine, the endless screw should be connected direct on the 

 drum-shaft. If the motive power is small, and if the soil 

 is stiff, and a greater depth of cultivation necessary, the 

 endless screw should be connected to the pole-socket shaft 

 as shown in the figure. If it is desired to work with horses , 

 the endless screw is removed, and the machine worked like 

 an ordinary horse-gin. The winding drum travels along the 

 headland on its rollers. The engine connected by the belt 

 follows it. It can also be used in a fixed position. 



Working. When this winding drum is worked with an 

 engine, it is preferable to install it in a stationary position, 

 the cable passing over a fixed pulley. The frequent dis- 

 placements of the engine necessitated entail considerable 

 loss of time. With animals, on the contrary, the displace- 

 ment can be quickly done. 



The only interesting peculiarity of this machine is the 

 adjustability of the speeds it is worked at, according to the 

 motive power, the state of the land, and the depth to be 

 ploughed. This adjustment of speed, the utility of which is 

 not apparent when horses are used, is, on the contrary, an 

 excellent item when steam-power is used, on account of the 

 varied power of engines. It is evidently important to work 

 rapidly when one has a 8 to 12 H.P. engine, and also to be 

 able to work the machine with an engine of 3 to 4 H.P. 

 only if necessary. 



GUYOT'S STEAM WINDING DRUM. 



The Guyot steam winding drum is a displacement capstan, 

 worked in a very ingenious manner. The portable engine 

 and the drum are carried on two strong iron beams, the 

 whole plant travelling on rails. The stability, therefore, is 

 very great, as the whole weight of the engine and drum is 

 opposed to the traction of the cable. The lateral displace- 

 ment is also rendered very easy. 



Description. The wheels of the portable engine rest on 

 two rolled joist girders, braced together at the required 

 distance apart. The capstan is fixed in front ; it consists of 

 a mechanical' drum (Fig. 26), on the shaft of which a cog- 

 wheel is keyed, gearing with a pinion, on the shaft of which 



