418 
PUEBTA DE LA SILEA. 
occultations of the satellites of Jupiter. I had previously 
determined the instant of the observation, but we missed 
them all, owing to some error of calculation in the Con- 
naissanee des Temps. The apparent time had been mis- 
taken for mean time. 
I was much disappointed by this accident; and after 
having observed at the foot of the mountain the intensity of 
the magnetic forces, before sunrise, we set out at live in the 
morning, accompanied by slaves carrying our instruments. 
Our party consisted of eighteen persons, and we all walked 
one behind another, in a narrow path, traced on a steep 
acclivity, covered with turf. We endeavoured first to reach 
hill, which towards the south-east seems to form a promon- 
tory of the Silla. It is connected with the body of the 
mountain by a narrow dyke, called by the shepherds the 
Grate, or Puerta de la Silla. We reached this dyke about 
seven. The morning was fine and cool, and the sky till then 
seemed to favour our excursion. I saw that the thermometer 
kept a little below 14° (11-2° Eeaum.). The barometer 
showed that we were already six hundred and eighty-five 
toises above the level^of the sea, that is, nearly eighty toises 
higher than at the Venta, where we enjoyed so magnificent 
a view of the coast. Our guides thought that ft would 
require six hours more to reach the summit of the Silla. 
We crossed a narrow dyke of rocks covered with turf • 
which led us from the promontory of the Puerta to the 
ridge of the great mountain. Here the eye looks down on 
two valleys, or rather narrow defiles, filled with thick vege- 
tation. On the right is perceived the ravine which descends 
between the two peaks to the farm of Munoz ; on the left 
we see the defile of Chacaito, with its waters flowing out 
near the farm of Gallegos. The roaring of the cascades is 
heard, whde the water is unseen, being concealed by thick 
groves of erythrina, elusia, and the Indian fig-tree.* No- 
thing can be more picturesque, in a climate where so many 
plants have broad, large, shining, and coriaceous leaves, than 
the aspect of trees when the spectator looks down from a 
great height above them, and when they are illumined by 
the almost perpendicular rays of the sun. 
* Ficus nymphseifolia, Erythrina mitis. Two fine species of mimosa 
are found in the same valley j Inga fastuosa, and I. cinerea. 
