Another popular error is that the diameter of the tile is the measure of its capacity, whereas the grade upon which it is laid is as important as the size of the tile. The extreme porosity of many of our soils, and the lack of thorough lateral drainage is another thing by reason of which main drains become over-taxed, simply because drainage water is not held in check by close soils, or distributed by lateral drains, but is brought in large quantities over the surface to the drain line, and must be taken away in a short time or injury is done to the land. In making mains or sub-mains it is better to err in making them too large than too small. MISTAKE NO. 5--NOT LATERAL ENOUGH. We expect too much from a single line of tile. We often see a line of tile put through a fifteen or twenty acre field with the expectation that the field will be drained, and thanks to our tractable soil, and the magic influence of tile, a great work is done for the field. It is, however, the dry weather drains previously alluded to. Put in the lateral drains so that the whole flat will come under the direct influence of tile, and you will have a garden spot instead of a field periodically flooded. Your sleep will not then be disturbed by fears that the morning will reveal your tiled field covered with water, and your corn crop on the verge of ruin. We often see a single line laid through a pond containing from one half to three acres. Ponds with such drainage always get flooded. Put in an abundance of laterals and the difficulty is overcome. I am glad to say that the tendency now among farmers who have practiced random drainage is toward more thorough work in this direction. The loss of an occasional crop soon demonstrates in favor of more thorough work. MISTAKE NO. 6--INATTENTION TO DETAILS.