82 INSTALLATION OF TEENCHING 



Plate II. shows the installation of the plant in the block ; 

 the traction cable a fastened to the plough L, winds 

 round the drum D ; the hauling-back cable b passes 

 over the fixed pulley m and winds round the drum E. 

 After each furrow has been turned, the system is displaced 

 in the direction of the arrow f, by an additional small 

 capstan, or on rails. The pulley m is displaced in the direc- 

 tion of the arrow f, for a distance equal to the width of 

 the sod. The pulley m is fixed by a chain d stretched 

 between two anchors. 



With the object of ploughing both ways with a balance- 

 plough, it has been proposed to install two gins, one on each 

 headland (Plate III.). The horses work alternately, as shown 

 in Fig. 50, but the part unploughed measures 32 to 39 

 feet on each side. This arrangement, which requires two 

 machines, is convenient when one cannot spare much time 

 for the operation. Under favorable conditions, it is possible 

 to plough \ acre per day with such an installation. 



It does not, however, do more work per horse per day. 

 Let us consider the following figures resulting from personal 

 observations in the field : A gin with two horses hauls a 

 plough at a rate of 2 inches per second, turning a sod 21 \ 

 inches wide and 1 5 inches deep ; the hauling back is done 

 by a horse travelling at a mean rate of 19 \ inches per 

 second. Assuming a length of furrow of 219 yards we 

 arrive at the following conclusions : 



System with 



1 Capstan. 2 Capstans. 



Number of horses yoked to the capstan ... 2 4 



// // for hauling back ... 1 



Total ... 3 4 



Time required to open one furrow : 

 Working forward ... ... 67 seconds 67 seconds 



Throwing the plough out, disconnecting 



the drum ... ... ... 2 n n 



Hauling back ... ... ... In n 



Starting the plough... ... ... 3 // n 



Balancing and starting the plough ... // 5 n 



Total per furrow ... ... 79 n 72 // 



Actual work done per hour : 



Length of furrow ... ... ... 166 feet 180 feet 



Surface ploughed (in square yards) ... 99yds. 108yds. 

 Surface ploughed per horse and per hour 



(in square yards) ... ... ... 32 // 27 i n 



The difference is quite as marked if four horses are used and 

 the speed of the plough greater. 



