The Isthmus appears to have been considerably uplifted and depressed during several geologic periods, some of the depressions carrying it below sea-level and thus uniting the Atlantic and the Pacific ocean and preventing the migration of land animals be tween North and South America. (G. McL. Wo.) The country has no lakes; the apparent exceptions are the arti ficial lakes, Bohio (or Gatun) and Sosa, of the Canal Zone. There are a few swamps, especially on the northern shore. But the drainage is good; about 150 streams empty into the Caribbean and some 325 into the Pacific. In the eastern part are three com plicated drainage systems of rivers very largely tidal. The largest is that of the Tuira (formerly called Rio Darien), whose head waters are near the Caribbean and which empties into the Pacific in the Gulf of San Miguel. The Chepo (or Bayano) also is a digi tate system with a drainage area reaching from the Caribbean to the Pacific; it is navigable for about 120 m. by small boats. The Chagres flows from a source near the Pacific south-west and then north to the Caribbean; is a little more than Ioo m. long and is navigable for about half that distance; it varies greatly in depth, sometimes rising 35 ft. in 24 hours (at Gamboa), and drains about i,000 sq.m. West of these three rivers are simpler and com paratively unimportant river systems, rising near the centre of the isthmus. Orographically the country is remarkable. The "exceed ingly irregularly rounded, low-pointed mountains and hills covered by dense forests" (Hill) are Antillean, not Andean, and lie at right angles to the axes of the systems of North and South America. The only regular ranges in Panama are in the extreme western part where the Costa Rica divide continues into Panama, and, immediately south of this and parallel to it, the Cordillera of San Blas, or Sierra de Chiriqui, where the highest peaks are Chiriqui (11,265 ft.) and, on the Costa Rican boundary, Pico Blanco (11,740 ft.) and Rovalo (7,020 ft.) ; there are two passes, 3,600 and 4,000 ft. high respectively. On the eastern boundary of the republic is the Serrania del Darien, an Andean range, partly in Colombia. The rough country between contains the following so-called "Sierras," which are not really ranges: in Veragua province, Sierra de Veragua, with Santiago (9,275 ft.) near the Chiriqui range, and Santa Maria (4,600 ft.), immediately north of the city of Santa Fe; in Los Santos province (Azuero Penin sula), bold hills rising 3,00o ft., and in Panama province, the much-broken Sierra de Panama, which has a maximum height of 1,700 ft. and a minimum, at the Culebra Pass, of 290 ft., the lowest point, except the interoceanic water-parting in Nicaragua, which is 153 ft., in the western continental system. There have been no active volcanoes since the Pliocene Tertiary period, but the country is still subject to dangerous earthquakes. There are a few plains, like that of David, in Chiriqui province, but irregular surface is normal; and this irregularity is the result of very heavy rains with a consequent extremely developed drainage system cutting river valleys down nearly to the sea-level, and of marine erosion, as may be seen by the bold and rugged islands, notably those in the Gulf of Panama. It is improbable that there has been any connection by water between the two oceans here since Tertiary time.
Climate.—The climate of most of Panama is entirely tropical, with warm days and cooler nights, the temperature at Colon varying from 68° to 95° F that for Panama is similar. The seasons are divided into wet and dry, the former from April to December, the rainfall being from 85 to 155 in. yearly. Panama was in former times literally a pest-hole from coast to coast.
Yellow fever and malaria were endemic, and smallpox and other scourges followed in their wake. The country is now probably the most healthy spot in the tropics, thanks directly to the mod em sanitation introduced by the American health authorities of the Canal Zone, whose authority is extended, by treaty, through out the republic.
Inhabitants.—The population of in 1930 was divided into racial classifications as follows: 78,814 whites, 69,582 negroes, Indians, 4,138 orientals and 272,028 mestizos or mixed bloods. The population figures of Panama are always given as distinct from the population of the Canal Zone, which is U.S. leased territory. (See PANAMA CANAL.) The country is very cos mopolitan and grows more so each year, owing to the increasing traffic of the canal and the varied ships that come there. The lower strata of the city populations, particularly Colon, at the northern or Atlantic terminus of the canal, are negro, however, chiefly from the British West Indies, or their descendants.
Panama is marked for the concentration of its population in towns, the chief of these being Panama (q.v.), at the Pacific or southern end of the canal, whose port is Balboa, the American city on the canal proper and within the Canal Zone. Colon, at the northern end of the canal, has as its port and sister town in the Canal Zone, Cristobal, from which it is separated only by an imaginary line. Ancon, which adjoins and is virtually a part of Panama city, is the Canal Zone town corresponding to Cristobal in its relation with Colon, but Ancon is not a port. Other towns of historic or commercial importance are Porto Bello, east of Colon on the Caribbean, the scene of Columbus's ill-fated colony of Nombre de Dios, the terminus of the causeway which traversed the isthmus in Spanish colonial days and the loading port of gal leons and thus the scene of the activities of the buccaneers; Bocas del Toro, now an important banana shipping centre; and David, the capital of Chiriqui Province, near the Pacific coast and Costa Rica.
Education.—Education is compulsory for children from 7 to 15 years of age. To furnish the facilities for making this law effective the Government had, in 1926, 446 schools, with pupils and 1,492 teachers, and there were 71 private schools. The National institute or university had 1,573 pupils, the normal school for girls, 696. There is also an arts and crafts school for boys. The Bolivarian university, founded at one of the ceremonies of a conference of Pan-American States at Panama in 1926, has the support of Panama, Colombia, Ecuador and Peru.
Panama Constitution was adopted on Feb. 13, 1904, and divides the Government into the three usual branches. The legislative power is vested in the national assembly, a single chamber with 46 members, elected for four years, a dep for every io,000 inhabitants. The president heads the execu tive, with a four-year term, and there is no vice president, the succession being provided by the selection by the national assem bly, of three "designates" every two years. The president, elected Aug. 5,1928, was Florencio Harmodio Arosemena. The presidential cabinet consists of five ministers as follows : of government and justice, of foreign relations, of finance and the treasury, of public instruction and of agriculture and public works. The judiciary consists of a supreme court of five judges appointed by the presi dent for a term of four years, a superior court, several circuit courts and various municipal courts. The judges of the superior and circuit courts are appointed by the supreme court for four years, the municipal judges by the circuit courts for one year.