[Illustration: View of the "Seracs".] These are usually situated on the edge of a plateau, and menace the whole valley beneath them. A slight movement of the glacier, or even a light vibration of the temperature, impels their fall, and occasions the most serious accidents. [Illustration: View of the "Seracs".] "Messieurs, keep quiet, and let us pass over quickly." These words, roughly spoken by one of the guides, checked our conversation. We went across rapidly and in silence. We finally reached what is called the "Junction" (which might more properly be called the violent "Separation"), by the Côte Mountain, the Bossons and Tacconay glaciers. At this point the scene assumes an indescribable character; crevasses with changing colours, ice-needles with sharp forms, seracs suspended and p