ACROSS UNKNOWN SOUTH AMERICA 
the valley to the north, we descended rapidly amidst 
luxuriant vegetation of tall bamboos, akun palms, and 
festooned liane, until we reached the Palmeira River, 
flowing from north to south. Having crossed it, we con¬ 
tinued for three and a half kilometres through dense vege¬ 
tation, and then recrossed it at a spot where it passed 
within enormous fissures in colossal masses of highly pol¬ 
ished, yellow lava. After solidification, these masses of 
lava had been subjected to violent commotion, as their 
stratification was nearly in a vertical position. 
Wherever possible I took observations for latitude and 
longitude, in order to ascertain my exact position; an 
eight-inch sextant, mercurial artificial horizon, and chro¬ 
nometers being used for the purpose. It is not easy to 
describe the torture you would have to endure when taking 
those tedious observations. The glass roof of the artificial 
horizon had unfortunately been broken. You would have 
to use great ingenuity in order to screen the mercury 
from the wind so as to obtain a well-defined reflection. 
No sooner would you get a perfect contact of the 
sun’s image and its reflection, than some huge fly or 
other insect would begin to promenade on the mercury, 
disturbing its surface. Butterflies were even more trouble¬ 
some, as they left upon the mercury — by the luminosity 
of which they were greatly attracted — sediments of 
multi-coloured powder and down from their wings and 
bodies. The mercury had to be carefully re-filtered before 
work could proceed. Then, what was worse, when both 
your hands were occupied — one holding the sextant, the 
other gently screwing the vernier — hundreds of mos¬ 
quitoes, taking advantage of your helpless condition, 
buzzed round and settled on your nose, ears, neck, eyelids, 
and forehead, stinging you for all they were worth. 
Swarms of bees — a dwarf kind, with body in yellow and 
black stripes; fortunately these did not sting — also 
placidly roamed upon every available patch of skin with 
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