Their Sting Is Indeed Comparatively Feeble, And They Use It Seldom; But A Person, Not Fully Convinced Of The Harmlessness Of These Angelitos, Can Scarcely Divest Himself Of A Sensation Of Fear.

I must confess, that, whilst engaged in my astronomical observations, I was often on the point of letting my

Instruments fall, when I felt my hands and face covered with these hairy bees. Our guides assured us that they attempt to defend themselves only when irritated by being seized by their legs. I was not tempted to try the experiment on myself.

The dip of the needle at the Silla was one centesimal degree less than in the town of Caracas. In collecting the observations which I made during calm weather and in very favourable circumstances, on the mountains as well as along the coast, it would at first seem, that we discover, in that part of the globe, a certain influence of the heights on the dip of the needle, and the intensity of the magnetical forces; but we must remark, that the dip at Caracas is much greater than could be supposed, from the situation of the town, and that the magnetical phenomena are modified by the proximity of certain rocks, which constitute so many particular centres or little systems of attraction.* (* I have seen fragments of quartz traversed by parallel bands of magnetic iron, carried into the valley of Caracas by the waters descending from the Galipano and the Cerro de Avila. This banded magnetic iron-ore is found also in the Sierra Nevada of Merida. Between the two peaks of the Silla, angular fragments of cellular quartz are found, covered with red oxide of iron. They do not act on the needle. This oxide is of a cinnabar-red colour.)

The temperature of the atmosphere varied on the summit of the Silla from eleven to fourteen degrees, according as the weather was calm or windy. Every one knows how difficult it is to verify, on the summit of a mountain, the temperature, which is to serve for the barometric calculation. The wind was east, which would seem to prove that the trade-winds extend in this latitude much higher than fifteen hundred toises. Von Buch had observed that, at the peak of Teneriffe, near the northern limit of the trade-winds, there exists generally at the elevation of one thousand nine hundred toises, a contrary current from the west. The Academy of Sciences recommended the men of science who accompanied the unfortunate La Perouse, to employ small air-balloons for the purpose of ascertaining at sea the extent of the trade-winds within the tropics. Such experiments are very difficult. Small balloons do not in general reach the height of the Silla; and the light clouds which are sometimes perceived at an elevation of three or four thousand toises, for instance, the fleecy clouds, called by the French moutons, remain almost fixed, or have such a slow motion, that it is impossible to judge of the direction of the wind.

Enter page number Go  Previous Next
Page 353 of 407
Words from 183146 to 183651 of 211363