OPERATIONS OP DRAINING. 109 



" This species of preparatory examination, by means 

 of pits, is therefore, in many cases, useful. It affords 

 the means of judging of the proper depth and dimensions 

 of which the drain shall be formed ; it prevents the com- 

 mitting of errors in the laying out of the lines of drains ; 

 and enables the drainer to enter into contracts with his 

 workmen with precision. 



" When we have thus, by sinking pits in various parts 

 of our intended lines, obtained an idea of the nature of 

 the ground, of the substances to be dug through, and of 

 the depth of the water, we mark our lines of drains upon 

 the ground. 



" This may be done by pins, or by a plough drawing 

 a furrow along the intended line. 



"It is at this time very convenient to make a hand- 

 sketch of the piece of ground to be drained, marking each 

 line as it is laid off in the field, and noting the depth and 

 direction in which the water is to run. 



" The hues being marked off in the manner described, 

 these are to form the upper edges of the drains. 



" The width of the drain at the top depends upon its 

 depth, it being usual, except in the case of very hard 

 and tenacious substances, to make it slope from the top 

 to the bottom. Thus, if it be 6 feet deep, and from 

 18 inches to 2 feet wide at bottom, it may be 2 J feet 

 wide at top. 



" But it is often impracticable to reach these substances 

 with a drain of common depth. In this case apertures 

 may be formed at the bottom of the drain, by boring or 

 sinking down at the proper distances, until the pervious 

 bed in which the water is contained is reached. By 

 this means the water will be allowed to flow up from be- 

 low into the cavity of the drain, and so will be carried 

 away. 



" The application of this principle had been familiar 

 from the remotest times in the sinking of wells. But it 

 was not till after the middle of the last century that the 

 same principle was applied to the draining of lands. This 

 was done by Mr. Elkington, of Warwickshire, who em- 

 ployed the auger and the boring-rod for the purpose of 

 10 XV. 



