extension) has a great influence on the minimum of this angle. The transparency of the mountain atmosphere at the equator is such that, in the province of Quito, as I have elsewhere noticed, the white mantle or Poncho of a horseman was distinguished with the naked eye at a horizontal distance of 84132 (89665 English) feet; therefore under a visual angle of 13 seconds. It was my friend Bonpland, whom, from the pleasant country seat of the Marques de Selvalegre, we saw moving along the face of a black precipice on the Volcano of Pichincha. Lightning conductors, being long thin objects, are seen, as has already been remarked by Arago, from the greatest distances, and under the smallest angles.
The accounts of the habits of the Condor in the mountainous districts of Quito and Peru, given by me in a monograph on this powerful bird, have been confirmed by a later traveller, Gay, who has explored the whole of Chili, and has described that country in an excellent work entitled Historia fisica y politica de Chile. The Condor, which, like the Lamas, Vicunas, Alpacas, and Guanacos, does not extend beyond the equator into New Granada, is found as far south as the Straits of Magellan. In Chili, as in the mountain plains of Quito, the Condors, which at other times live either solitarily or in pairs, assemble in flocks to attack lambs and calves, or to carry off young Guanacos (Guanacillos). The ravages annually committed among the herds of sheep, goats, and cattle, as well as among the wild Vicunas, Alpacas, and Guanacos of the Andes, are very considerable. The inhabitants of Chili assert that, in cap-
