In the history of the discovery of Guiana much obscurity prevails; but Martin Silva, in 1568, obtained a patent to conquer some tribes to the westward of the present limits. After penetrating through Venezuela, his people deserted him; when he returned to Spain, and collected new followers. Silva then attempted to cross the country from the coast between the Maranon and Orinoco, but he and his followers were slain and devoured by the Caribs. The missionaries, Pizarro's brother, and Diego Ordaz, also attempted to enter and explore Guiana, but were all frustrated by the natives. Sir Walter Raleigh also twice tried to reach the pretended city of Manoa, or El Dorado, which is supposed to have been situated in lake Parima, and whose streets were paved with gold; which marvellous story had most probably its origin in an Indian village, built on an island whose soil contained mica, which glittering, and appearing splendid in the sunshine, deceived the adventurers who had observed it. In later times the Spaniards have endeavoured to conquer these regions, but have always been unsuccessful; one of them has had the courage to cross the greater part of the country in the dress of an Indian; and from his researches, the direction of the ranges of mountains has been ascertained. Humboldt, also contrived to go a great distance along the chain of the cataracts, but was prevented from exploring the sources of the Orinoco and the celebrated lake of Parima by the _Guayecas_, a race of Indians who, though of very diminutive stature, display the utmost courage and activity in defending their possessions. These people resist all persuasion to become the converts of the monks who had visited their frontiers, and equally defy the armed force which generally accompanies these priests. The rivers flowing through Guiana, which are best known, are the _Orinoco_, into which, on the north, the _Caroni_, the _Aruy_, the _Caura_, and several smaller ones empty themselves; on the west the _Suapure_, the _Sippapu_, &c., join that stream, while on the south the _Guaviare_, the _Ynritta_ and the _Atabapo_ also add to the magnificence of its course. The _Rio Negro_ also flows through a part of Guiana, and forms, by means of the _Cassiquiari_, a junction between the Maranon and the Orinoco, thus constituting Guiana an immense island detached in every direction by a broad expanse of water from the continent of South America. The _Yapura_ and the _Uapes_ run through the southern or continental parts of this province, and join the Maranon. Many large rivers issue from, or rise near lake Parima and the interior; of which _Rio Branco_ and the _Siaba_ are the most noted, but as the lake itself, and all the surrounding country are as unknown as the internal parts of Africa, it will be useless to repeat names that are gathered from maps, often imaginary, and generally erroneous.