On his way down the River Gila to its mouth, Pattie visited races then all but unknown, including the Yotans, Eiotaws, Papawans, Mokees, Umeas, Mohawas, and Nabahoes, with whom but very little intercourse had yet been held. On the banks of the Rio Eiotario he discovered ruins of ancient monuments, stone walls, moats, and potteries, and in the neighbouring mountains he found copper, lead, and silver mines. We owe a curious travelling journal also to Doctor Willard, who, during a stay of three years in Mexico, explored the Rio del Norte from its source to its mouth. Lastly, in 1831 Captain Wyeth and his brother explored Oregon, and the neighbouring districts of the Rocky Mountains. After Humboldt's journey in Mexico, one explorer succeeded another in Central America. In 1787, Bernasconi discovered the now famous ruins of Palenque. In 1822, Antonio del Rio gave a detailed description of them, illustrated with drawings by Frederick Waldeck, the future explorer of Palenque, that city of the dead. Between 1805 and 1807, three journeys were successively taken in the province of Chiapa and to Palenque by Captain William Dupaix and the draughtsman Castaneda, and the result of their researches appeared in 1830 in the form of a magnificent work, with illustrations by Augustine Aglio, executed at the expense of Lord Kingsborough. Lastly, Waldeck spent the years 1832 and 1833 at Palenque, searching the ruins, making plans, sections, and elevations of the monuments, trying to decipher the hitherto unexplained hieroglyphics with which they are covered, and collecting a vast amount of quite new information alike on the natural history of the country and the manners and customs of the inhabitants. We must also name Don Juan Galindo, a Spanish colonel, who explored Palenque, Utatlan, Copan, and other cities buried in the heart of tropical forests. [Illustration: View of the Pyramid of Xochicalco. (Fac-simile of early engraving.)] After the long stay made by Humboldt in equinoctial America, the impulse his explorations would doubtless otherwise have given to geographical science was strangely checked by the struggle of the Spanish colonies with the mother country. As soon, however, as the native governments attained to at least a semblance of stability, intrepid explorers rushed to examine this world, so new in the truest sense, for the jealousy of the Spanish had hitherto kept it closed to the investigations of scientific men.