530 



NATURE 



{April'], \\ 



Payta. Nowhere in the world are the forests more 

 hixuriant than in the former place, whereas, on arriving 

 at Payta, Mr. Ball was informed by the officers of the 

 ship that it was no use his ta'dng his botanical box 

 ashore with him, because the country was absolutely 

 without vegetaiion. As, however, the forewarned ex- 

 pected, this was not quite the case : stunted bushes grew 

 in the cliffs, nor were plants absent on the plateau above, 

 wliere, however, the vegetation was more scarce than he 

 had anywhere seen it, except in the tract west of the 

 Nile above Cairo. He remarks that the gullies farrowing 

 the seaward face of the plateau show that heavy rains 

 must visit this part of the coast, and on inquiry he was 

 informed that abundant rain, lasting for several days, 

 recurs at intervals of three or four years. This, he subse- 

 quently found, is a normal feature of the rainless zone, 

 added to which he was informed that slight showers occur 

 at intervals a few times in the year, which suffice to 

 maintain the vitality of the few species of plants that 

 hold the ground persistently ; whilst the heavier rains are 

 followed by an outburst of herbaceous vegetation covering 

 the surfaces that have long been bare. 



F"or the existence of this rainless zone Mr. Ball con- 

 siders that the hitherto assigned causes are insufficient. 

 These are : the influence of the Andes in condensing the 

 .Atlantic vapours brought by the westward atmospheric 

 flow ; the warming in its passage north of the vapour- 

 bearing aerial currents that accompany the Antarctic or 

 Humboldt oceanic current ; and the effect of this 

 warming of the air in enabling it to hold in suspense 

 all the vapour it absorbs in its passage north, Mr. 

 Ball's principal objections to the sufficiency of these 

 causes are that the Andes of Ecuador and Columbia 

 do not condense the western vapour-bringing winds, 

 whilst those of Peru, Bolivia, and North Chili do ; and 

 that the littoral zone of the former regions is, for a 

 distance of Soo miles, even moister than parts of the 

 coast of Brazil and Guiana. His supplemental explana- 

 tion is based chiefly on the physical features of the 

 .Andes. In Peru the .Andes present four parallel longi- 

 tudinal chains, increasing in mean elevation in going 

 westward, though the highest peaks are not on the 

 westernmost range. In Ecuador only two such ranges, 

 the two westernmost, exist, and these do not suffice to 

 drain the vapour bringing winds, a portion of whose 

 moisture is precipitated on the Pacific coast. In 

 Columbia, again, there are three of these parallel ranges, 

 enough perhaps to drain the easterly winds ; and its 

 sources of moisture may be supposed to be derived from 

 the diversion southwards of easterly currents from the 

 Caribbean Sea which have crossed the Isthmus of 

 Panama. On the whole, however, Mr. Ball considers 

 that the influence of the Humboldt currents, oceanic and 

 aerial, is of far greater moment than is that of the Andes, 

 since the influence of these currents is felt even to the north 

 of the Gulf of Guayaquil, as at Cape St. Elena, where 

 the rains are less frequent than at Guayaquil. For the 

 further description of this interesting subject we must 

 refer to the work itself 



On April 15, Callao, the port of Lima, was reached, and 

 a ten days' expedition to the higher Andes was effected. 

 For this there were two railroad facilities. One line starts 

 from the coast at Mollendo, south of Callao, and, running 



by Arequipa, crosses the crest of the Andes, and ter- 

 minates at Lake Titicaca, i2,Soo feet above the sea. The 

 other starts from Lima itself It was projected with the 

 intention of piercing the crest of the Cordilleras at an 

 elevation of 15,645 feet above the sea, thence descending 

 to Oroya, a plateau between the main ranges. Its ulti- 

 mate object was to afford a route to the fertile districts on 

 the eastern slopes of the Andes. As yet it has only 

 reached a village called Chicla, 12,200 feet above the sea, 

 its progress having been stopped by the war between 

 Peru and Chili. The first of these routes was ob- 

 viously the most desirable for a naturalist, but want of 

 time and the fact of Arequipa being in possession of a 

 Peruvian force drove Mr. Ball to take the Chicla route. 

 To the professed naturalist Mr. Ball's observations on 

 this little expedition offer much of interest, but the 

 season was unfavourable for botanising, the weather at 

 the culminating point wretched, and the natural features 

 of the country, under such conditions at any rate, 

 anything but inviting. There is a brief discussion on 

 mountain sickness, of which Mr. Ball has already detailed 

 his symptoms in this journal (vol. xxvi. p. 477). They are 

 anomalous ; but as his elevation was only 12,200 feet, at 

 which many mountaineers who suffer acutely at 16,000 feet 

 and above it feel no inconvenience at all, his experience 

 is insufficient. That the symptoms should disappear 

 during bodily exercise is opposed to what is described in 

 the cases not of man only, but of cattle, sheep, and 

 horses, in crossing high passes. The observations on the 

 temperature of the upper Andean regions as compared 

 with that of the coast are very valuable, as are the notes 

 on the zones of vegetation, the ranges of species, the 

 distribution of endemic forms, &c. 



On his return to Lima, Mr. Ball obtained some further 

 information regarding the well-known hollowed cliffs of vol- 

 canic rock which occur along the coast, and reach to 700 

 feet above it, and which have been written of by Lyell and 

 others as indications of a rise of the land. According to a 

 veryintelligentlocalobserver, Mr. William Nation, of Lima, 

 the excavations are due chiefly to a cryptogamic plant 

 which grows on the surface of the cliff's, and is in active 

 vegetation as a disintegrating agent during the dense fogs 

 that prevail for many months of the year. Mr. Nation 

 thinks that alternations of dry and damp air, by causing 

 the cells of this burrowing plant to expand and contract, 

 effect the removal of scales of mineral matter from the 

 surface of the rock, and hence eventually excavate the 

 latter. Fancying that the plants might (as do some 

 lichens) chemically affect the rock, Mr. Ball submitted 

 specimens to an eminent cryptogamist, who found it to be 

 an Alga, and harmless in this respect. Mr. Ball himself 

 is disposed to think that vicissitudes of temperature 

 aided by alternations of moisture and dryness, dry fog 

 and sun, may play the greatest part in effecting the 

 hollows. It is to be hoped that Mr. Nation will follow- 

 up the problem, which wants only careful observation to 

 solve it. 



Between Callao and Coquimbo, along a monotonous 

 coast, several places were visited, but these seem 

 to be far from being oases ; some of them, indeed, are 

 dependent on transport by sea for a supply of fresh water. 

 The track between .Arica and Copiapo, a distance of 600 

 miles, " further than from Liverpool to Opo'rto," is that in 



