It is estimated that there are about 5,000 independent Indians on the Isthmus east of Costa Rica. Of these, it may be presumed that there are not 2,000 capable of bearing arms; a small number when dispersed in the highlands between Costa Rica and Chocó, but quite enough to molest small parties of workmen very seriously.
For defensive purposes, as well as for the general order and discipline of very large bodies of laborers, in a wild country, some degree of military organization and an acquiescence in military discipline would seem to be indispensable.
Whether convicts might be employed advantageously may be a subject for grave consideration. In clearing the wood of a tropical forest, and exposing ground to the sun's rays for the first time, much pestilential sickness may be caused, as has been repeatedly proved (at Pulo Penang, Fernando Po, and many other places). It cannot be doubted that convicts would be peculiarly liable to the influence of such diseases, and therefore it might be unwise to make such an experiment. Natives of tropical climates, or Chinese, would probably be able to stand the malaria of newly cleared ground far better than Europeans.
The most formidable, because permanent and irremediable, obstacle is unquestionably the climate. There is no doubt that rain prevails about two thirds of the year, even on the higher grounds of Darien; while it is no less certain that in the gulf of San Miguel (where mangrove jungles bound low, muddy shores, and the great fall of tide exposes extensive mud-banks) there is a continued succession of rains, more or less heavy, except during short intervals. Examine any travellers' accounts, read their narratives—they themselves bear witness to the undeniable fact, although in general terms they may say there is not so much rain, and it is not so unhealthy, as has been supposed.
Many Europeans state they did not suffer, although much and continuously exposed to the rains and heat. Active and temperate men have not found the climate very detrimental. Persons who have had many years' experience there assert that care and regularity will ward off such attacks of fever or dysentery as are common among thoughtless Europeans unaccustomed to tropical regions.
It is possible that the great rise of tide on the south side of the Isthmus may tend to purify the air on its shores, and this effect, in such a place as San Miguel Gulf, may be very beneficial.
On the Atrato, at Chagres, at Portobello, and other notoriously unhealthy places, there is little or no rise of tide; and the air among the mangrove jungles becomes at times pestilential. Seemann, in his Voyage of the Herald, recently published, gives so correct a description of such places that it deserves attention. He says (vol. i. p. 249): 'The sea-coast, and those parts influenced by the tides and the immediate evaporation of the sea, produce a quite peculiar vegetation, which is generally characterized by a leathery, glossy foliage, and leaves with entire margins. In all muddy places, down to the verge of the ocean, are impenetrable thickets formed of mangroves, which exhale putrid miasmata, and spread sickness over the adjacent districts. Occasionally, extensive tracts are covered with the "Guagara de puerco," its fronds being as much as 10 feet high. Myriads of mosquitoes and sand-flies fill the air. Huge alligators sun themselves on the slimy banks, lying motionless, blinking with their great eyes, and jumping into the water directly any one approaches. To destroy these dreaded swamps is almost impossible.'
Again (pp. 251, 252), he says: 'Forests cover at least two thirds of the whole territory. The high trees, the dense foliage, and the numerous climbing plants, almost shut out the rays of the sun, causing a gloom which is the more insupportable as all other objects are hidden from view. Rain is so frequent, and the moisture so great, that the burning of these forests is impossible.' 'From reading the highly colored accounts with which many travellers have endeavored to embellish their narratives, the European has drawn, in imagination, a picture of equinoctial countries which a comparison with nature at once demolishes.'
Speaking of the 'vegetable ivory,' and referring to the climate, Mr. Seemann says (p. 222): 'It grows in low, damp localities, and is diffused over the southern parts of Darien and the vicinity of Portobello, districts which are almost throughout the year deluged by torrents of rain, or enveloped in the thick vapor that constantly arises from the humidity of the soil and the rankness of the vegetation.'
Describing the appearance of one of these mangrove forests, as they may be called, the same author observes (p. 73): 'The trees were actually in the water. The tall mangroves, with roots exposed for 12 or 14 feet, formed a huge tangled trellis-work, from which the tall stems rose to a height of 60 or 70 feet.' Fitzroy's Further Considerations on the Great Isthmus of Cent. Am. March 1853, in Jour. Roy. Geog. Soc., xxiii. 176-87.