TABLE 4.—Monthly meteorological data, year 1914, Culebra, Canal Zone. Month. Mean maxi mum. Minimum. Date. Mean mini mum. Maximum daily range. Mean wet thermome Mean Mean ter. temperature dew point. relative humidity. TABLE 6.-Monthly evaporation, Canal Zone, years 1914 and 1915. NOTE.-Insulated tanks 10 inches in diameter at Balboa Heights and Colon. Water surface protected from action of sun and rain. Exposed pans 4 feet in diameter and 10 inches deep floating in water at Rio Grande and Gatun. For monthly evaporation during past years see previous annual reports. TABLE 8.-Seismograph records, Balboa Heights, Canal Zone, year ended June 30, 1915. [Latitude 8° 58' north; longitude 79° 33′ west.] [100 K Bosch-Omori seismographs. Greenwich mean time, midnight to midnight.] 125 K instruments, magnification 8. (N.-S. 18 35 40 IN.-S. E.-W. (?) E.-W. 9 26 20 E.-W. 15 33 00 9 27 40 15 36 00 15 36 00 9 40 15 9 40 05 5 34 13 2 No record on instruments, seismograph room being painted. 3 25 K component substituted. 100 K N-S. instrument broken by painter. NOTE.-Station formerly Ancon, moved to Balboa Heights, Oct. 1. 1914. Period of pendulum, 25 seconds; magnification, 10; damping medium. The amplitude indicates half of the complete range of maximum motion. Laska's formula used in computing distances of remote earthquakes (620 miles or more), and Omori's formula for earthquakes less than 620 miles distant. HYDROGRAPHY. GENERAL. The important feature of the year was the advent of Gatun Lake and the canal as an international waterway. During the period between September 26, 1913, and August 15, 1914, there was some shifting of floating equipment, and several sugar barges and rafts of piles were locked through the locks. On August 15, 1914, the canal was opened for commercial use; Gatun Lake was at elevation 85 at that time. It was raised to 86 between September 12 and 17, to 86.70 between November 17 and 22, and to 87 between December 12 and 13; during the whole wet season almost daily spillway gate operation was necessary to maintain the level desired. During March, 1915, the evaporation and other losses so exceeded the yield as to lower the lake to 86.60 or 0.4 of a foot. On April 3 and 4, 1915, the lake was lowered to 85.50. On June 28, 1915, the spillway was closed and the lake was at 85.96 on July 1, 1915. Little difficulty was experienced in controlling the lake levels within a variation of 0.1 foot by the operation of not more than five spillway gates. It was expected that, owing to the hydroelectric plant using about three times the amount of water allowed for in the original estimates, there would be a deficit during the dry-season months of 1915. However, the lake actually lost but 0.4 of a foot. The spillway discharges from the freshets of February 9, 10, and 11, 1915, and April 3-4, 1915, alone, had they been stored, would have raised the lake from 87 to 89.95. |