part of the valley, which opens toward Cape Blanco. In going from Caraccas, we pass near the great barracks of San Carlos over a barren and rocky soil. Scarcely a few plants of argemone mexicana are to be found. The gneiss appears every where above ground. We might have fancied ourselves on the table-land of Freiberg. We crossed first the little rivulet of Agua Salud, a limpid water, which has no mineral taste, and then the Rio Caraguata*. The road is commanded on the right by the Cerro de Avila and the Cumbre; and on the left, by the mountains of Aguas Negras. This defile is very interesting in a geological point of view; at this spot the valley of Caraccas communicates by the vallies of Tacagua and of Tipe with the coast near Catia. A ridge of rock, the summit of which is forty toises above the bottom of the valley of Caraccas, and more than three hundred toises above the valley of Tacagua, divides the waters which flow into the Rio Guayra and toward Cape Blanco. On this point of division, at the entrance of the branch, the view is highly pleasing. The climate changes as we descend toward the west. In the valley of Tacagua we found some new habitations, conucos of maize and plantains. A very extensive plantation of tu

Gneiss, hor. 12, dip 70° west.

ną, or cactus, stamps a peculiar character on this barren country. The cactuses reach the height of fifteen feet, and grow in the form of candelabras, like the euphorbiums of Africa. They are cultivated in order to sell their refreshing fruits in the market of Caraccas. The variety destitute of thorns is called, whimsically enough, in the colonies, tuna de Espana. We measured at the same place magueys, or agaves, the long stem of which, loaded with flowers, was fortyfour feet high. However common this plant is become in the south of Europe, a person born in a northern climate is never wearied of admiring the luxury of vegetation, the rapid developement of a liliaceous plant, which contains at once a sweet juice, and astringent and caustic liquids, employed in the cure of wounds to consume proud flesh.

We found several veins of quartz in the valley of Tipe appearing above the soil. They contained pyrites, carbonated iron ore, traces of sulphuretted silver (glasserz), and gray copper ore, or fahlerz, The works which had been undertaken, either to extract the ore, or to explore the nature of it's bed, appeared to be very superficial. The earth falling in had filled up those excavations, and we could not judge ourselves of the richness of the lode. Notwithstanding the expense incurred under the intendancy of Don Jose Avalo, the great

question, whether the province of Venezuela contains mines rich enough to be wrought, is yet problematical. Though in countries where hands are wanting, the culture of the soil demands unquestionably the first care of government, yet the example of New Spain is sufficient to prove, that the working of metals is not always unfavourable to the progress of agriculture. The best cultivated Mexican fields, those which recall to the memory of the traveller the most beautiful parts of France and the south of Germany, extend from Silao toward the Villa of Leon: they are in the neighbourhood of the mines of Guanaxuato, which alone furnish a sixth part of all the silver of the New World.

NOTES TO THE FOURTH BOOK.

NOTE A.

The end of the eclipse of the Sun, on the 28th of October, 1799 (Chapter X, p. 312 of this volume), presented me with a very remarkable phenomenon, which I shall describe, as I "Looking find it noted in my Astronomical Journal. through Dollond's large achromatic telescope very steadfastly (at 458 by the chronometer) at the darkened part of the Sun's disk, I saw three or four luminous dots, appear and disappear successively. They were like stars of the fifth magnitude. I thought for some moments, that this phenomenon was owing to the explosion of volcanoes in the moon, the existence of which is admitted by Herschell, but which Don Antonio Ulloa considers as holes, that pass through the planet. What was my astonishment, when, toward the end of the eclipse, at 5h 37 by the chronometer, I perceived two similar luminous dots beyond the disk, at an arc of twelve or fifteen minutes distance from the limb which had not been eclipsed! The eclipse ended at 52, 48′37′′ by the chronometer. These two luminous dots appeared only once. light was of the intensity of a star of the third magnitude I could not explain to myself this appearance. My eye was not at all fatigued."

Their

Louville relates (Mem. de l'Acad., 1715, p. 96) having seen at London, during the total eclipse of the Sun on the 3d of May 1715,"6 fulminations, or instantaneous vibrations of luminous rays. They appeared, during the total darkness, on the surface of the moon, so that I thought I saw trains of