Ten miles of line were run that day, through the solemn pine forest, and darkness overtook the party on the very summit of the great Continental Divide. They were crossing the Sierra Madre Mountains, through Zuñi Pass. As Glen subtracted the last reading of his rod for the day from the last height of instrument, and found that it gave an elevation of 7925 feet, he uttered a shout. For weeks the elevations above sea-level had been steadily mounting upward. This one was a foot lower than the last.