90 INSTALLATION OF TRENCHING 



WORK OF HORSE WINDING DRUMS. 



The quantity of practical work done by a horse winding 

 drum depends on the following conditions : 



Power of the team. 



Resistance of the plough. (Nature of soil and dimen- 

 sions of block.) 

 State of material. 

 Dimensions of block, and arrangement of plant. 



The power of the team and the resistance offered by the 

 soil are in relation to the section of the sod and the speed of 

 the plough. That speed, together with the width of the sod 

 and unavoidable losses of time, determine the amount of 

 work done per hour. 



The state of material bears by its mechanical yield on the 

 traction power available on the plough. 



The dimensions of the block, and arrangement of the plant, 

 more or less favorable to the work, influence the time lost 

 in proceeding from one furrow to another ; for instance, the 

 longer the furrow the less the loss of time. However, other 

 considerations may modify the arrangement of the plant, for 

 instance, in very stiff soil it is advisable to run the furrows in- 

 such directions as to follow the fall of the ground to assist 

 drainage of the water in the subsoil. 



For light soils the season of ploughing has not a very great 

 influence on the results of the operation. In clayey soils it 

 is advisable not to plough when they are too wet, as the 

 mould-board always exerts a certain compression on the 

 sod, which makes it cling together like a brick, and forms 

 large compact clods, often remaining in that state for many 

 years. 



The staff necessary for working the plant is generally in- 

 creased by 'a few men, who remove large stones, roots, arid 

 bushes, which it is detrimental to leave in the ground. 



The following is an example of the method of calculating 

 the practical work of a trenching or subsoiling plant : 



Yards. Yards. Yards. 



Length of furrow ... 219 219 219 



Speed of plough (inches per 



second) ... ... 2 2-75 3-94 



