DRAINAGE. 109 



course laid with larger pipes. Experience has established 

 this average, that a 3-inch pipe will discharge the water of 

 9 acres, 4 of 16, and so on ; the quantity of acres being 

 equal to the product of the diameter of the pipe in inches 

 multiplied into itself. 



We were astounded to find at the conclusion of Mr. 

 Parkes's Newcastle Lecture this sentence: "It may be 

 advisable for me to say, that in clays, and other clean-cut- 

 ting and firm-bottomed soils, I do not find the collars to be 

 indispensably necessary ; although I always prefer their 

 use." This is a barefaced treachery to pipes : an abandon- 

 ment of the strongest point in their case the assured 

 continuity of the conduit Every one may see how very 

 small a disturbance at their point of junction would disso- 

 ciate two pipes of 1 inch diameter. One finds a soft place 

 in the bottom of the drain, and dips his nose into it 1 

 inch deep, and cocks up his other end. By this simple 

 operation the continuity of the conduit is twice broken. 

 An inch of lateral motion produces the same effect. Pipes 

 of a larger diameter than 2 inches are generally laid with- 

 out collars ; this is a practice on which we do not look with 

 much complacency ; it is the compromise between cost and 

 security, to which the affairs of men are so often compelled. 

 No doubt a conduit from 3 to 6 inches in diameter is much 

 less subject to a breach in its continuity than one which is 

 smaller ; but when no collars are used, the pipes should be 

 laid with extreme care, and the bed which is prepared for 

 them at the bottom of the drain should be worked to their 

 size and shape with great accuracy. 



To one advantage which is derived from the use of col- 

 lars we have not yet adverted the increased facility with 

 which free water existing in the soil can find entrance into 

 the conduit. The collar for a 1^-inch pipe has a circum- 

 ference of 3 inches. The whole space between the collar 

 and the pipe on each side of the collar is open, and affords 

 no resistance to the entrance of water ; while at the same 

 time the superincumbent arch of the collar protects the 



