Note 218 — CHAP. XVI. Of Ridges.

The natural Course of Water being downwards, it would always run by the nearest Way to the Bottom of the Hill, if nothing stopt it; but the Water runs from an Hill in Two Manners; viz. Upon the Surface of the Staple, and upon the Surface of the Clay that is under the Staple; that which runs under keeps its strait Course from the Top to the Bottom of an Hill, under a Ridge that is made exactly with the Descent of the Hill, except that Part of the Water that rises up into the Mould, and a very little that soaks into the Furrows, for when the Furrows are not made exactly with the Descent, the more oblique they are to the Descent, the longer will be the Water’s Course under the Ridges; and the shorter, as they are nearer being at Right Angles to the Descent. ’Tis also the same with the Water that falls upon the Surface of the Ridges; for the more horizontal they are, the shorter its Course will be from them to the Furrows, which carry it off; and the less of the Water will sink into the Ridges, the less oblique and the nearer to Right Angles to the Descent they are made.