... down the lineof steepest descent cannot be parallel, and, consequently, the97Fig. 20 - MAP WITH DRAINS AND CONTOUR LINES.x Draining for Profit, and Draining for HealthFig. 24 - SILT-BASIN, BUILT ... collars.) For 20 acres 3-1/2 inch pipes For 40 acres 2 3-1/2 inch pipes or one 5-inch sole-tile. For 50 acres 6 inch pipes sole-tile. For 100 acres 8 inch pipes or two 6-inch sole-tiles.It is not ... acreagehas been saved. Not, however, being confident as to the soil11No. 5 was one inch in diameter; No. 4, about 1-1/3 inches.90 Draining for Profit, and Draining for Healthhaving already...