YARROW DAM.–The Yarrow dam of the Liverpool Water-Works is a notable example of the second type, (a section of which is shown in Fig. 2.) An excavation 97 ft. in depth was made to bed rock through different strata of varying thickness, and a trench 24 ft. wide was cut with side slopes 1 on 1 for the first 10 ft. in depth below the surface. The trench was then carried down through sand, gravel and boulders with sides sloping 1 in 12. The upper surface of the shale bed rock was found to be soft, seamy and water-bearing. Pumps were installed to keep the water out of the trench while it was being cut 4 or 5 ft. deeper into the shale. The lower portion was then walled up on either side with brickwork 14 ins. in thickness, and the trench between the walls was filled with concrete, made in the proportion of 1 of cement, 1 of sand and 2 of gravel or broken stone. By so doing a dry bed was secured for the foundation of the puddle wall. Two lines of 6-in. pipes were laid on the bed rock, outside of the walls, and pipes 9 ins. in diameter extended vertically above the top of the brickwork some 27 ft. These pipes were filled with concrete, after disconnecting the pumps. After refilling the trench with puddle to the original surface, a puddle wall was carried up simultaneous with the embankment, having a decreasing batter of 1 in 12, which gave a width of 6 ft. at the top. This form of construction is very common in England and Figs. 14 and 15 show two California dams, the Pilarcitos and San Andres, of the same general type. [Illustration: FIG. 14.–CROSS-SECTION OF PILARCITOS DAM.] [Illustration: FIG. 15.–CROSS-SECTION OF SAN ANDRES DAM.] ASHTI EMBANKMENT.–This is not a very high embankment, but being typical of modern dams in British India, where the puddle is generally carried only to the top of the original surface of the ground, and not up through the body of the dam, it is thought worthy of mention. Fig. 16 shows a section of this embankment, which is located in the Sholapur District, India. The central portion of this dam above the puddle trench is made of “selected black soil;” then on either side is placed “Brown Soil,” finishing on the outer slopes with “Murum.” Trap rock decomposes first into a friable stony material, known in India as “Murum” or “Murham.” This material further decomposes into various argillaceous earths, the most common being the “black cotton soil” mentioned above. [Illustration: FIG. 16.–CROSS-SECTION OF ASHTI TANK EMBANKMENT.] This particular dam has been adversely criticised on account of the lack of uniformity in the character of the materials composing the bank. It is claimed that the materials being of different density and weight, unequal settlement will result, and lines of separation will form between the different kinds of materials.