The deep, irregular crevasses common to most glaciers were bridged by crust formations of the recent autumnal snows. These bridges were so uniform with the general surface of the glacier as to make their detection almost impossible. Although Sonntag moved with great caution and continually tested the snow with his ice-chisel, which replaced the Alpine alpenstock, he broke through one bridge. Most fortunately the fall was at a place where the fissure was only about three feet wide, opening either way into a broad crevasse. Still more fortunately he did not fall entirely into the chasm, but as he pitched forward he instinctively extended his left hand, in which he was carrying a mercurial barometer three feet long, which caught on two points of the glacier and thus barely saved his life.[11] But Sonntag's ardent wish was for a bear hunt which occurred during an unsuccessful attempt to revisit Rensselaer Harbor by dog-sledge, when a bear and cub were killed. Hayes says: "Sonntag has given me a lively description of the chase. As soon as the dogs discovered the trail they dashed off utterly regardless of the safety of the people on the sledges. Jensen's sledge nearly capsized, and Sonntag rolled off in the snow, but he was fortunate enough to catch the upstander and with its aid to regain his seat. The delay in the hummocks gave the bears a start and made it probable that they would reach the open sea. Maddened by the detention and the prospect of the prey escaping them, the bloodthirsty pack swept across the snowy plain like a whirlwind. The dogs manifested the impatience of hounds in view of a fox, with ten times their savageness. To Sonntag they seemed like so many wolves closing upon a wounded buffalo. "The old bear was kept back by the young one, which she was unwilling to abandon. The poor beast was in agony and her cries were piteous. The little one jogged on, frightened and anxious, retarding the progress of the mother who would not abandon it. Fear and maternal affection alternately governed her. One moment she would rush forward toward the open water, intent only upon her own safety; then she would wheel around and push on the struggling cub with her snout and again coaxingly encourage it to greater speed. "Within fifty yards of the struggling animals the hunters, leaning forward, slipped the knot which bound the traces together in one fastening, and the dogs, freed from the sledges, bounded fiercely for their prey. The old bear heard the rush of her enemies and squared herself to meet the assault. The little one ran frightened around her and then crouched for shelter between her legs.