The salubrity of climate for which Tacna is distinguished is considered to be partly owing to its vicinity to the cold of the mountains, (for the snowy pass of the Cordillera, which leads to upper Peru, is within four hours’ ride of this town,) and still more to a fine dry plain between it and the sea, which only wants water to become rich in agricultural produce.[33] But in its present state it is free from that malaria which the humidity attendant on irrigation would not fail to engender here as well as in other parts of the coast. In its environs cotton grows spontaneously; and the native women collect it, and make thread from it by means of the _spindle_, just as we have often seen done in some of the warmer inland valleys, where the cotton is indigenous. It is a fact, not perhaps undeserving of notice, that a bud cut off a cotton-tree in the neighbourhood of Arica or Tacna was hung up in the cabin of an English merchant-ship, preserved its vitality in the navigation round Cape Horn, and opened when about half-way between Peru and England. The whole coast of upper Peru—now called Bolivia—is arid and desert; so much so, that the celebrated president Santa Cruz—who, much to the prejudice of Arica,[34] made Cobija a free port for the introduction of merchandise,—found that he could not, by sinking pits in the deep sands of Cobija, come at a supply of good water.[35] For want of water and lucern, mules from the interior of Bolivia often die at the sea-port of Cobija; for there is no vegetation within a great distance from this place. The little water that is obtained at Cobija is brackish, like that in the pozo or well of the great castle at Callao,[36] which has invariably been observed to give disorder of the bowels to the soldiers, who, during the sieges which that fortress has sustained, were obliged to drink of it. The same has been observed at Cobija, and therefore there are boats kept there for the purpose of conveying water to it from Paquisa and other distant parts, which makes it an expensive necessary of life. On several parts of the coast of Peru, water, even for domestic uses, is very scarce; and in the dry season wells are often dug in the beds of dried-up rivers, or in other places in the neighbourhood of irrigated lands. At Port Bermejo and Casma, between nine and ten degrees of south latitude, we are told by the Spanish coasting pilots that, dig where you will, at ten or twelve paces from the sea, you are sure of finding water at the depth of half a fathom that is not very brackish. Wells or pits, however, thus opened in different parts of the coast, are often found to dry up as they do in Lima (where they are common enough) during the dry season, which is the time when they are most required.