About midnight
They suffered much with the cold , as the nights were keen enough to create ice an inch in thickness , and the frosts destroyed a great deal of the herbage on which the horses subsisted . The third day the sky began to grow heavy in the morning , and as the air was keen they feared snow would fall , but it partially broke away before night , greatly to their satisfaction . They lay down by their camp-fire with the stars gleaming , though faintly , above them . About midnight they were awakened by flakes of snow falling on their faces , and on awaking , they discovered the ground white around them . Before morning the white covering was three inches deep . The winter had set in uncommonly early , and they with saddened hearts rode all day through the falling snow . Night came on , and scraping the ground clear of leaves and snow , they built themselves a temporary shelter , leaving one side open , by which the camp-fire was built .