M. Bourdiol, Civil Engineer, with a party of fifteen persons—afterward increased to twenty by the addition of some natives—proceeded carefully, cutting their way, and chaining and leveling at the rate of about a mile a day. Reaching the Chuquanaqua below the junction of the Sucubti, he was compelled to desist, by the approach of the rainy season. He returned to Panama after an absence of sixty days. The nearest approach to a determination of a pass by M. Bourdiol appears in the rather equivocal statement, that the origin of the valley of Monti is one hundred and eighty-two metres (about 597 feet). If all of these explorers had left some permanent mark at the termination of their surveys, succeeding parties could have taken up the line where the former left off, and the determination of a practicable route could have been made in one-half the time now required. M. Bourdiol affirms that he verified the height of the Sucubti, as given by Codazzi and Gisborne, but it is not apparent how he found the same points determined by these engineers. Where so many failed, with every accessory and advantage likely to assure success, the pertinent inquiry suggests itself, Is there any one fact in common which may serve to explain failures so universal? All find difficulties in cutting the way, requiring natives accustomed to the use of the machete; all are misled by imperfect maps, which fail to give the altitude of the passes and the true course of the rivers. While one party is turned back by the rainy season, another is stopped by the Indians, another by want of time. But one party succeeded in crossing from sea to sea, but under such circumstances that each day was a struggle for existence, to the exclusion of the scientific objects of the expedition. The hostility of the Indians, although not always stated, appears to have been the chief obstacle to a careful exploration; and internal dissension concurred to bring failure upon the best appointed of these expeditions. The following table presents, at one view, all that is known of the Darien routes: