Two rollers were in use constantly, each drawn by six horses. One weighed five tons and the other eight tons, giving respectively 166 and 200 lbs. pressure per lin. in. They were not grooved, but the smooth surface left by the rollers was always harrowed and cut up more or less by the loaded wagons passing over the surface previously wetted. The wagons when loaded gave 750 lbs. pressure per lin. in., and the heavy teams traveling wherever they could do the most effective work compacted the materials better even than the rollers.

Several test pits which were dug into the dam during construction showed that there were no distinct lines traceable between the layers and no loose or dry spots, but that the whole mass was solid and homogeneous.

A careful record is being kept of the amount of settlement of the Tabeaud Dam. It will be of interest to record here the fact that just one year after date of completion the settlement amounted to 0.2 ft., with 90 ft. depth of water in the reservoir.

Water was first turned into the reservoir five months after the dam was finished. The very small amount of settlement here shown emphasizes more eloquently than words the author’s concluding remarks relating to the importance of thorough consolidation, by artificial means, of the embankment. ([See p. 64, Secs. 6 to 8.])

OUTLET TUNNEL.–The outlet for the reservoir is a tunnel 2,903 ft. in length, through a ridge of solid slate rock formation, which was very hard and refractory. At the north or reservoir end of the tunnel, there is an open cut 350 ft. long, with a maximum depth of 26 ft.

Near the south portal of the tunnel and in the line of pressure pipes connecting the “petty reservoir” above with the power-house below, is placed a receiver, connected with the tunnel by means of a short pipe-line, 60 ins. in diameter.

A water-tight bulkhead of brick and concrete masonry is placed in the tunnel, at a point about 175 ft. distant from the receiver. In the line of 60-in. riveted steel pipe, which connects the reservoir and tunnel with the receiver, there is placed a cast iron chamber for entrapping silt or sand, with a branch pipe 16 ins. in diameter leading into a side ravine through which sand or silt thus collected can be wasted or washed out. By the design of construction thus described, it will be seen that all controlling devices, screens, gates, etc., are at the south end of the tunnel and easily accessible.

WASTEWAY.–The wasteway for the reservoir is an open cut through its rim, 48 ft. in width and 300 ft. long. The sill of the spillway is 10 ft. below the crown of the dam. The reservoir having less than two square miles of catchment area, and the feeding canals being under complete control, the dam can never be over-topped by a flood. [Fig. 3] shows the relative location of the dam, outlet tunnel and wasteway channel.

Almost the whole of the embankment forming the Tabeaud Dam, not included in the foundation work, was built in less than eight months. The contractor’s outfit was the best for the purpose the writer has ever seen. After increasing his force from time to time he finally had the following equipment: