The depth of 4.13, in Fig. 21, as well as the other depths at the points at which the grade changes, happen to be those found by the computation, as hereafter described, and they are used here for illustration.
The figures in this table, as well as in the next preceding one, are adopted for the published profile of drain C, Fig. 21, to avoid confusion. In ordinary cases, the points which are fixed as the basis of the computation are given in round numbers;—for instance, the depth at C3 would be assumed to be 4.10 or 4.20, instead of 4.13. The fractions given in the table, and in Fig. 21, arise from the fact that the decimals are not absolutely correct, being carried out only for two figures.
The drains, which are removed a little to one side of the lines of stakes, may be turned toward the basin from a distance of 3 or 4 feet.
The foot of the measuring rod should be shod with iron to prevent its being worn to less than the proper length.
"Talpa, or the Chronicles of a Clay Farm."
When chips of tile, or similar matters, are used to cover openings in the tile-work, it is well to cover them at once with a mortar made of wet clay, which will keep them in place until the ditches are filled.
Surely such soil ought not to require thorough draining; where men can go so easily, water ought to find its way alone.
The land shown in Fig. 21, is especially irregular, and, for the purpose of illustrating the principles upon which the work should be done, an effort has been made to make the work as complete as possible in all particulars. In actual work on a field similar to that, it would not probably be good economy to make all the drains laid in the plan, but as deviations from the plan would depend on conditions which cannot well be shown on such a small scale, they are disregarded, and the system of drains is made as it would be if it were all plain sailing.
Klippart's Land Drainage.
Klippart's Land Drainage.