Bower did not utter a syllable until they struck out toward the center of the glacier. A crevasse some ten feet in width and seemingly hundreds of feet deep, barred the way; but a bridge of ice, covered with snow, offered safe transit. The snow carpet showed that a number of climbers had passed quite recently in both directions. Even Helen, somewhat awed by the dimensions of the rift, understood that the existence of this natural arch was as well recognized by Alpinists as Waterloo Bridge is known to dwellers on the south side of the Thames. "Now, Miss Wynton, you should experience your first real thrill," said Bower. "This bridge forms here every year at this season, and an army might cross in safety. It is the genuine article, the first and strongest of a series. Yet here you cross the Rubicon. A mixture of metaphors is allowable in high altitudes, you know." Helen, almost startled at first by the unaffected naturalness of his words, was unfeignedly relieved at finding him restored to the normal. Usually his supply of light-hearted badinage was unceasing. He knew exactly when and how to season it with more serious statements. It is this rare quality that makes tolerable a long day's solitude _a deux_. [Illustration: She flourished her ice axe bravely. _Page 163_] "I am not Caesar's wife," she replied; "but for the credit of womankind in general I shall act as though I was above suspicion--of nervousness." She did not look round. Barth was moving quickly, and she had no desire to burden him with a drag on the rope. When she was in the center of the narrow causeway, a snow cornice in the lip of the crevasse detached itself under the growing heat of the sun and shivered down into the green darkness. The incident brought her heart into her mouth. It served as a reminder that this solid ice river was really in a state of constant change and movement. Bower laughed, with all his customary gayety of manner. "That came at a dramatic moment," he said. "Too bad it could not let you pass without giving you a quake!" "I am not a bit afraid." "Ah, but I can read your thoughts. There is a bond of sympathy between us." "Hemp is a non-conductor." "You are willfully misunderstanding me," he retorted. "No. I honestly believed you felt the rope quiver a little." "Alas! it is the atmosphere. My compliments fall on idle ears." Barth interrupted this play of harmless chaff by jerking some remark over his shoulder. "Looks like a _guxe_," he said gruffly. "Nonsense!" said Bower,--"a bank of mist. The sun will soon melt it." "It's a _guxe_, right enough," chimed in Karl, who had recovered his power of speech. "That is why the boy was blowing his horn--to show he was bringing the cattle home." "Well, then, push on. The sooner we are in the hut the better." "Please, what is a _guxe_?" asked Helen, when the men had nothing more to say.