In spite of the late hours kept by most of the engineers that night, their camp was broken by daylight, and at sunrise they were off on the line as usual, for September was now well advanced, and there were mountain ranges yet to be crossed that would be impassable after winter had once fairly set in. So, leaving the pleasant army post and their hospitable entertainers in it, they picked up their line, and, running it out over the broad San Luis Valley to the Rio Grande, began to follow that river into the very heart of New Mexico.