The siphons are formed of cast-iron socket pipes, 3.65 m. (12 ft.) long, caulked in the ordinary way with lead joints. The thickness of the 45.7-cm. (18-in.) pipes is 19 mm.; that of the 50.8-cm. pipes is 21 mm. On the steep hillsides the pipes are anchored securely to the rock in concrete blocks reinforced with heavy iron chains. In some cases these siphons were difficult of access, but ox-teams hauled the pipes in a very efficient and satisfactory manner. _Overflow Chambers._--The ordinary overflows, of which there are 14, are similar in design to the siphon inlets. _Testing, etc._--When the line was completed it was tested for water-tightness, and the loss was found to be about 5%, part of which was probably due to absorption. At a later date it was found that the waters of the Estanzuela River, which contain 150 parts of calcium carbonate (CaCO_{3}) per million, deposited a very fine film of lime on the interior of the pipes, completely filling any pores there might have been. At the present time there is no measurable leakage, thus proving that the character of the work is very satisfactory. The water was turned into the conduit on June 11th, 1908, and delivered to the city on the following day through a by-pass, before the reservoir was completed. The pipe line is patrolled daily by an inspector with the authority of a gendarme, so as to prevent the unlawful abstraction of water, a very necessary precaution in so dry a country. SOUTH DISTRIBUTING RESERVOIR. The distributing reservoir for the Estanzuela supply is at Guadalupe, on the foot-hills to the south of the Santa Catarina River, about 2 km. from the center of the city. The reservoir is a covered one, of reinforced concrete, and its capacity is 38,000,000 liters (10,000,000 U. S. gal.). [Illustration: PLATE VIII, FIG. 1.--GENERAL VIEW OF EXCAVATION AND EMBANKMENT FOR SOUTH RESERVOIR BEFORE LINING.] _Excavation and Embankment._--The heavy slope of the ground at the selected site made the circular form the most desirable. On the low side the ground was excavated about 2 m. below the original ground line, while the excavation at the upper part of the slope was about 12 m. deep. The excavated material consisted chiefly of sillar and limestone conglomerate, which when broken up forms a calcareous clay of an excellent character for the formation of embankments, when proper care is taken. The dimensions fixed for the internal diameter of the finished concrete work of the reservoir were: 81 m. (265.68 ft.) at the top, and a depth of water of 9 m., with sides sloping 55 in 100. [Illustration: FIG. 10.--SOUTH RESERVOIR PLAN OF EXCAVATION.]