Notwithstanding the dangers to be encountered from the fierce Caribs-- who, sheltered by trees and rocks everywhere, attacked their foes with poisoned arrows--and the numerous disappointments which occurred, fresh bands of adventurers, age after age, still believing in the fabled wealth which was to be their prize should they succeed, set forth, in hope of reaching the wonderful city. Some of Sir Walter Raleigh's followers declared, indeed, that they saw rocks shining brightly with gold, and a mountain containing diamonds and other valuable stones, the lustre of which blazed forth to a considerable distance. Every marvellous fable found belief. The crew of an English ship, about that time exploring the Marowyne, stated that they had seen on its banks a gigantic race of men, who carried in their hands bows made of gold. Wherever mica was seen glittering on the side of a mountain, it was supposed to be the same precious metal. Sir Walter Raleigh sent his faithful lieutenant, Captain Keymis, to carry on the expedition he was himself unable to undertake. His chief object, and that of his successors, was to discover the site of the golden city. Keymis, while sailing up the Essequibo, heard that by ascending one of its tributaries--the Rupunoony--he would certainly reach it. Numerous other expeditions were organised by Spaniards and Portuguese. Many of the unfortunate adventurers fell by the hands of the natives, others by famine and fatigue; and as late as the year 1776 a large band set forth, when many hundreds perished, one man only returning to tell the sad fate of his companions. At length, in the quarter to which Captain Keymis had been directed, the small lake of Amucu was discovered, to which a river called the Parinia is connected; and from the geological structure of the surrounding country, is supposed to have been formerly much larger than at present. Within and around it are islands and, rocks of mica, slate, and talc; "the materials," observes Humboldt, "out of which has been formed that gorgeous capital, whose temples and houses were overlaid with beaten plates of gold." Schombergh, who visited the lake, agrees with the German philosopher. Another traveller, Hillhouse, in 1830 ascended the Masaruni, which flows from the northern side of the mountains of Roraima, among which the lake is situated; and believes that its romantic valley was once the bed of a large lake twelve miles in width, and upwards of one hundred miles in length,--which long ago burst its barriers and gave rise to the fable still preserved among the Indians, and, till within almost the present century, believed in by the colonists themselves. RIVERS:--THE ESSEQUIBO. Let us take a glance over some of the rivers of the land.