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pital admissions were lower than any similar period since sanitary operations have been conducted

on the present scale.


The true source of the Chagres has never been accurately determined. It has, however, two principal branches, one (the larger) known as the Pequeni, rising in the Cordillera San Blas, which at that point forms the Continental Divide, very close to the Atlantic Coast. The other branch has its origin about twenty miles (by the river), above Alhajuela, at which point the French Canal Company established a gauging station.

Between Alhajuela and the Caribbean, the principal tributaries are the Gatun, Chilibre, Obispo, Gatuncillo and Trinidad, named in the order their of joining the Chagres. In the dry season these inay be regarded as negligible, but during rainy months they become tropical torrents, with a volume not to be ignored. None of the tributaries have been followed to their source, with the exception of the Obispo, although the Isthmia. Canal Commission has established gauging stations on the Trinidad and Gatuncillo, about eight miles above Gatun.

Few rivers show a greater variation in the amount of discharge at different periods of the year than the Chagres. In the dry season, it is a clear, quietly flowing stream, while during the rainy season it becomes a great river, subject to sudden and violent freshets and floods.

The following table shows the maximum, the minimum and the mean discharges at each of the three principal gauging stations operated by the Isthmian Caval Coinmission:


A scene on the Chagres River~Panama. Isthmian-American & PAR News Agency & stdvertising Surnau. M. Bienkomst

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Name of Station Years of Ob- Maximum Dis. Minimum Dis. Mean Yearly

servation charge in cubic charge in cubic Discharge in

feet per second feet per second cubic ft. per sec. Date

Dato Alhajuola 1899 to date 92,000 12-3-06 240

A pl. 01

2360 Gamboa 1882 to date

Except 1889 & ) 76,000 12-3-06 240 Apl. 01 3046
some months

1890 to date
108,000 12-4-06 240


Apl. 01

The gauging station at Gatun was established in May 1907, and while discharges have been measured there since that time, the observations have not been carried on for a sufficient time to permit their use as authoritative. Enough data has been secured however, from measurements made this year, to enable us to compute the discharge at 135 per cent. of that at Bohio.

The following table taken from the revised edition of General Abbot's book "Problems of the Panama Canal" will show the maximum discharge reached in the eight greatest floods of the Chagres of which there is authentic record.


Max. Discbarge in cubic ft. Max. Mischarge in cubic ft,
Date height

per sec.
Per height

per sec.

Per above Maxuuni In 48 hours cent a bo ve Maximum In 48 hours cent low wa

low water in ft.

ter in ft. Nov. 1906 22.10 40,075 25.003 62 26.08. 46,292 38,738 83 Dec. 1906 35.65 76,006 42,377 56 38.65 108,000 74,371 69

1893 25.33 43,086 27,971 65 28.54 51, 100 43,590 85 1890 31.82

65,371 34,752 54 32.15 71,660 51,068 71 1888 31.37 58,132 48,278 83 34.68 79,000 Nov. 1885 31.50 64,488 43,404 67 33.79 74.800 Dec. 1885 24.11 44,923 32,421 72 26.41 47,466 1879* 36.65 78,614

39.37 112, 730 *Note : The height reached during this food was recorded only for Bohio; that at

Gamboa being calculated by means of the relation, which has been found to exist between those two stations by subsequent observations.

The Chagres above Gamboa is a clear mountain stream, and in the dry season the amount of matter carried in suspension is so small that no observations were deemed necessary.

However, experiments were made by the Isthmian Canal Commission of 1899-1901 in order to determine the amount of matter carried in suspension during the rainy season, with the following results: At Alhajuela it was found that the matter in suspension was .15 of one per cent of the total volume of the water, and at Bohio .18 of one per cent.

As the result of a chemical analysis of the water of the Chagres by Dr. Arthur I. Kendall

, Acting Chief of the Isthmian Canal Commission Laboratory, collaborating with Ricardo M. Arango, Division Engineer in charge of the hydrographic work of the Commission, it was found that at Gamboa there is an average of 228 parts of solid matter carried in suspension to every million parts of water.

In the course of the Chagres river from the Sierra San Blas, its bed presents varied geologic formations. At its source granite is found and pieces have been washed down, but little is known of the exact character of the country. Above Alhajuela, there is stratified limestone, sometimes. white but usually gray, which passes under the sandstone of the lower river. Lower down, between Alhajuela and Cruces, a compact calcareous sandstone presents itself, containing fossils of the upper Oligocene or Miocene period, while the bed of the river at Gamboa is composed of compact limestone. At Bohio, there is a fine-grained volcanic breccia, and at Gatun a moderately close conglomerate under a brownish, impure calcareous clay, the former containing fossils of the Oligocene age. Between Gatun and Limon Bay, the Chagres passes through a stretch of swampy lowlands reaching almost to the sea, where the river cuts through a range of low hills.

Meteorological Work on the Isthmus.

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This work could not be considered as fairly established by the Isthmian Canal Commission until January 1, 1906, when there were in operation two first class meteorological stations-Ancon and Naos, and twelve rainfall stations, Cristobal, Gatun, Bohio, Tabernilla, Bas Obispo, Gamboa, Alhajuela, Empire, Culebra, Rio Grande, La Boca and Panama. Of these, the stations at Ancon, Naos, Cristobal, Rio Grande and Bohio were using self-registering instruments. During the year Brazos Brook, Bas Obispo, Empire, Camacho, Culebra and La Boca were supplied with self-registering instruments and Bas Obispo was established as a first class meteorological station. This station is also equipped with an up-to-date evaporation plant, where experiments are being conducted to ascertain the daily, monthly and annual amount of evaporation. The Naos station was discontinued January 1, 1908, and consolidated with Ancon.

During the year 1907, Cristobal was established as a first class meteorological station, and the stations at Alhajuela, Gatun and Bohio equipped with triple registering instruments for recording the wind direction and velocity, sunshine, and rainfall.

There are now in operation on the Canal Zone three first class meteorological stations, at which the following observations are taken: Barometric pressure, temperature,

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