two o’clock
Internal fractures and rents were already commencing , the work of destruction and decomposition was proceeding rapidly , aided by the imprisoned air-bubbles ; and the fragility of the huge structure , built up by the cold , was manifest to every eye . It could not survive the Arctic winter , it was doomed to melt beneath the sunbeams , and it contained material enough to feed large rivers . Lieutenant Hobson had warned his companions of the danger of the avalanches which constantly fall from the summits of the icebergs , and they did not therefore go far along their base . That this prudence was necessary was proved by the falling of a huge block , at two o'clock , at the entrance to a kind of valley which they were about to cross . It must have weighed more than a hundred tons , and it was dashed upon the ice-field with a fearful crash , bursting like a bomb-shell . Fortunately no one was hurt by the splinters . From two to five o'clock the explorers followed a narrow winding path leading down amongst the icebergs ; they were anxious to know if it led right through them , but could not at once ascertain .