30 TRENCHING AND SUBSOILING 



The gin hauls a trenching plough, built specially for it 

 by Durand, of Montereau (Seine-et-Marne), This implement 

 (Fig. 11) is of very great power, and allows land to be 

 ploughed easily to a depth of 2 feet. It has three coulters 

 with a steel share, made in such a way as to keep the 

 plough well into the ground. All the regulating may be 

 done during work without stopping, by means of a hand- 

 wheel acting on screws ; a small wheel is fixed at the rear 

 of the plough to take it back to new ground. This wheel 

 revolves on a lever, at the extremity of which is a hook. 

 During the ploughing the small wheel lifts automatically and 

 revolves on the bottom of the furrow opened by the plough. 

 To carry the plough, the swingle bar is secured to the hook of 

 the lever ; the traction of the horse lowers it, and at the 

 same time forces the small wheel to rest on the ground, 

 lifting the frame and allowing the plough to run on three 

 wheels. This small wheel is articulated so as to form a fore- 

 carriage replacing the truck. The plough weighs 13 cwt. 

 3 qr., and costs 38. 



GRUB'S DOUBLE WINDING-DRUM GIN. 



Grue also makes a double winding-drum gin, allowing* 

 the plough to be worked both ways and avoiding the time 

 lost in pulling the plough back to new ground. 



Description. This gin is composed of two drums, each 

 winding a cable. One of these is fastened directly on the 

 plough, the other one, which is longer, passes over a fixed 

 pulley anchored on the opposite headland, and is then made 

 fast to the plough ; these two drums may at will run loose on 

 their shafts or be keyed on to them. It is easy to understand 

 that these two drums will alternately wind and unwind the 

 cable, drawing the plough backwards and forwards, there- 

 fore the ploughing will take place both ways without loss of 

 time. The plough in this case must evidently be either a 

 turn-wrest plough or a balance plough, turning the sod on 

 the same side during its passage both ways. (See Figs. 12 

 and 27.) 



In this case the difficulties again reside in anchoring 

 the pulley. Gru6 solved the difficulty in the following 

 wa y . Three iron beams, 10 feet in length, are placed 

 one above the other with a space of 4 inches between each. 

 Corresponding holes are punched out of each beam, and 

 a spindle serving as axle to the pulley passed through 



