DRAINAGE. 107 



quod ubique, quod inter omties " is, if we remember right, 

 a sufficient ground of faith ; but, on argument, the water 

 must get into the drain, and must get into the pipes. This 

 is a matter on which we have seen even sensible men so 

 muddle-headed that we fear we must be elementary. We 

 will assume the drain to be 4 feet deep, and the water-table 

 to be at 1 foot below the surface of the earth. Every par- 

 ticle of water which lies at 3 feet below the water-table has 

 on it the pressure of a column of water 3 feet high ; this 

 pressure will drive the particle in any direction in which it 

 finds no resistance, with a rapidity varying inversely to the 

 friction of the medium through which the column acts. 

 The bottom of our drains will offer no resistance, and into 

 it particles of water will be pushed, in conformity with the 

 rule which we have stated : rapidly, if the medium opposes 

 little friction ; slowly, if it opposes much. The water so 

 pushed in runs off by the drain, the column of pressure 



brought one 3-inch pipe and three of 4 inches each. They lie side by 

 side, and water flows perennially through each of them. Near to this 

 outlet did grow a red willow. In February, 1852, I found the water 

 breaking out to the surface of the ground about 10 yards above the 

 outlet, and was at no loss for the cause, as the roots of the red willow 

 showed themselves at the orifice of the 3-inch and of two of the 4-inch 

 pipes. On examination I found that a root had entered a joint between 

 two 3-inch pipes, and had .travelled 5 yards to the mouth of the drain, 

 and 9 yards up the stream, forming a continuous length of 14 yards. 

 The root which first entered had attained about the size of a lady's 

 little finger ; and its ramifications consisted of very fine and almost silky 

 fibres, and would have cut up into half a dozen comfortable boas. The 

 drain was completely stopped. The pipes were not in any degree dis- 

 placed. Boots from the same willow had passed over the 3-inch pipes, 

 and had entered and entirely stopped the first 4-inch drain, and had 

 partially stopped the second. At a distance of about 50 yards a black 

 Italian poplar, which stood on a bank over a 4-inch drain, had com- 

 pletely stopped it with a bunch of roots. The whole of this had been 

 the work of less than 18 months, including the depth of two winters. 

 A 3-inch branch of the same system runs through a little group of 

 black poplars. This drain conveys a full stream in plashes of wet, and 

 some water generally through the winter months, but has not a peren- 

 nial flow. I have perceived no indication that roots have interfered 

 with this drain. I draw no general conclusions from these few facts, 

 but they may assist those who have more extensive experience in draw- 

 ing some, which may be of use to drainers. T. G. 



