414 SWINE IN AMERICA 



with coarse galvanized wire screen. It is well to fur- 

 ther protect this outlet pipe and screen by setting four 

 posts in a square around the pipe and about two feet 

 from it. Coarse wire screen may be used to inclose the 

 space between the posts, or old boards may be put on if 

 good-sized cracks are left. This will prevent the outlet 

 from being covered so soon when the conditions are sucli 

 that the pond fills in with the wash brought down with 

 the water. The pipe should extend 20 to 30 feet outside 

 of the dam, to enable placing the watering tank away 

 from the soft, seepy ground that is often found just 

 below the dam. It is well to put in a cut-off valve near 

 the tank. 



"After the form and location of the base of the dam 

 have been determined, the area of it should be plowed. 

 If the soil is full of roots, or covered with grass, it is 

 best to scrape it off as deep as the plowing and plow up 

 the area again, leaving the base loose and rough before 

 earth for the bank is put down. This will aid in pre- 

 venting seeping at the bottom of the dam. To make a 

 good strong embankment for a pond, the sides should 

 slope about 45 degrees, or in other words, one foot in 

 width to every one in height. If the labor is not very 

 expensive and other work not crowding, i>^ to one 

 will be a better pitch for the bank, particularly on 

 the slope on the inside of the pond. The top of the 

 dam should be three to four feet wide and after the dam 

 has settled, one to three feet above the level of the pond 

 when full. The height of the top above this level should 

 be such that the water will not go over the dam during 

 a freshet except at the spillway, as that is what washes 



