The main drain was extended, temporarily during construction, from the central trench (Fig. 4), to the up-stream toe of the dam. This was cut 5 or 6 ft. deep into solid rock, below the general level of the stripped surface. Fig. 6 is reproduced from a photograph of this trench. An iron pipe 2 ins. in diameter was imbedded in Portland cement mortar and concrete, and laid near the bottom of the trench. At the point (B) where the quartz vein (already described) intersected this drain, two branch drains were made, following the fault well into the hill on both sides. Figs. 7 and 8 are views of the North and South trenches, respectively. These trenches were necessary to take care of the springs issuing along the quartz vein. This water led to a point (N, Fig. 4) near the up-stream toe, by means of the drain shown in Fig. 9. The lateral drains and that portion of the main central drain extending from their junction (B) to a point (N) about 230 ft. from the axis of the dam have pieces of angle iron or wooden Y-fluming laid on the bottom of the trenches immediately over the 2-in. pipe, as shown in Figs. 7, 8 and 9. These are covered in turn with Portland cement mortar, concrete, clay puddle and earth fill. The water will naturally flow along the line of least resistance, and consequently will follow along the open space between the angle irons and the outside of the pipe until it reaches the chamber and opening in the pipe, permitting the water to enter and be conveyed through the imbedded pipe-line to the rear drain. This point of entry is a small chamber in a solid cross-wall of rich cement mortar, and is the only point where water can enter this pipe-line, the two branches entering the wells and the stand-pipe at their junction (soon to be described) having been closed. That portion of the foundation between the axis of the dam and the quartz vein, a distance of about 160 ft., was very satisfactory, without fissures or springs of water. In this portion the 2-in. pipe was imbedded in mortar and concrete without angle irons, and the continuity of the trench broken by numerous cross-trenches cut into the rock and filled with concrete and puddle. It is believed that no seepage water will ever pass through this portion of the dam. If any should ever find its way under the puddle and through the bed rock formation, the rear drain, with its hillside branches, will carry it away and prevent the saturation of the lower or down-stream half of the dam. [Illustration: FIG. 10.–VIEW OF TABEAUD DAM WHEN ABOUT HALF COMPLETED.]