THE VEGETATION OK THE JUAN FERNANDEZ ISLANDS 813 



offers safe anchorage. Very likely wind conditions are the same around Masa- 

 fuera, where the higher south half, to judge from the character of the vegetation, 

 receives a very large amount of precipitation. Bahfa Toltcn west of the North 

 cape generally offers some shelter for small craft, even if landing is not always 

 possible and anchorage unsafe with winds north of SW. The West coast is re- 

 ported always to be inaccessible. As a rule vessels anchor outside Quebrada 

 de las Casas on the ICast coast, from where it is easy to reach the interior of 

 the island, but as winds east of S are frequent, landing is rarely comfortable 

 and often hazardous or quite impossible. 



Light conditions. 



Some observations were made on the strength of light, measured with an ac- 

 tinometer based on the principle of exposing photographic paper and comparing 

 with a standard shade. If the light at midday in the open is set = i, the follow- 

 ing figures were obtained. 



Primeval rain-forest 1/20— 1/45, under a closed roof of Dicksojiia ^\nVm^\.o 

 iioo; in the bottom of a narrow gorge, filled with Dicksonia 1/420 was found. 

 Where Aristotelia niaqiii formed part of the undergrowth, 1/30 — 1/40 was ob- 

 served, but where the maqui dominates, light decreased to 1/180 — 1/250, and 

 once, in a very dense, pure macal, 1/2000 was observed. No native species will 

 germinate under such conditions. The BoeJimeria groves may be quite dark, 

 150 or less. The brushwood at the foot of the elevated ridges, where rosette- 

 trees are common, get much more light, 1/3 — 1/8 as observed, and the same holds 

 good for the scrub. In the canyons of Masafuera conditions vary a great deal; 

 from 1/2 near the entrance to i/io in the narrows, under overhanging walls down 

 to I / 1 00. 



The climate of Masatierra as compared luith the climate of the coast zone of the 



7nainland of Chile. 



In my paper of 1914 (j. 53) I made a comparison between Masatierra and 

 a number of coast stations in Chile and came to the conclusion that the island 

 climate shows a more favourable combination of temperature and rainfall than 

 any other station: where the temperature is higher or as high as in Masatierra, 

 the precipitation is considerably smaller, and where the rainfall is greater, the 

 temperature is lower. I had, however, only few observation series; the figures 

 in tables VII — XI are based on a much better material. 



Whereas temperature conditions at Pta Angeles (Table VII) differ little 

 from those of Masatierra, the rainfall is much smaller and the summer very dry 

 — a climate of a pronounced "Mediterranean" type. 



The temperatures at Pta Carranza (Table VIII) are about the same as in 

 alt. 345 m on Masatierra, but the precipitation much smaller. 



The Tumbes station (Table IX) was moved several times. From 1901 to 191 9 the 

 altitude was 91 m, from 1920 to 1925, 120 m, 1926 — 1927 127 m, 1921 — 1931 120m, 

 1932 115 m, 1933 — 1937 120 m, 1938 127 m, from 1939 120 m. As the differences 

 in altitude are slight, the stations were here treated as one. At Tumbes we still 



