together in an individual, ensure the attainment of valuable results from a great and important journey.” In discussing the question respecting the sources of the Orinoco, I will begin with the conjectures which I had myself formed on the subject. The dangerous route travelled in 1739 by the surgeon Nicolas Hortsmann, of Hildesheim; in 1775 by the Spaniard Don Antonio Santos, and his friend Nicolas Rodriguez; in 1793 by the Lieutenant-Colonel of the 1st Regiment of the Line of Para, Don Francisco Jose Rodriguez Barata; and (according to manuscript papers, for which I am indebted to the former Portuguese Ambassador in Paris, Chevalier de Brito) by several English and Dutch settlers, who in 1811 went from Surinam to Para by the Portage of the Rupunuri and by the Rio Branco;--divides the terra incognita of the Parime into two unequal portions, and serves to limit the situation of a very important point in the geography of those regions--viz. the sources of the Orinoco, which it is no longer possible to remove to an uncertain distance to the East, without interfering thereby with what we know of the course of the Rio Branco, which flows from north to south through the basin of the Upper Orinoco; while that river itself, in this part of its course, pursues for the most part an East and West direction. From political reasons, the Brazilians, since the beginning of the present century, have testified a lively interest in the extensive plains east of the Rio Branco. See the memoir which I drew up at the request of the Portuguese court in 1817, “sur la fixation des limites des Guyanes Française et Portuguaise” (Schoell, Archives historiques et politiques, ou Recueil de Pièces officielles, Memoires, &c. T. i. 1818, p. 48-58). Viewing the position of Santa Rosa on the Uraricapara, the course of which appears to have been determined with tolerable accuracy by Portuguese engineers, the sources of the Orinoco cannot be looked for east of the meridian of 65-1/2° from Paris, (63°.8′ W. long. from Greenwich). This being the eastern limit beyond which they cannot be placed, and considering the state of the river at the Raudal de los Guaharibos (above Caño Chiguire, in the country of the surprisingly fair-skinned Guaycas Indians, and 52′ East of the great Cerro Duida), it appears to me probable that the upper part of the Orinoco does not really extend, at the utmost, beyond the meridian of 66-1/2° from Paris (64°.08′ W. from Greenwich.) This point is according to my combinations 4°.12′ West of the little lake of Amucu, which was reached by Sir Robert Schomburgk.