I mention these features because the best route to the summit of Mont Blanc lies over the glaciers and snow fields and between the walls of the great trough I have described, and the first station is at the Grands Mulets, where a cabin for the accommodation of climbers has existed for many years. From the foot of the Aiguille du Midi, at the Pierre a l'Echelle, across the Glacier des Bossons to the rocks of the Grands Mulets the distance is about a mile and a quarter, and the perpendicular increase of elevation nearly two thousand feet. The passage seldom presents any difficulty, except to inexperienced persons, although at times many crevasses must be crossed, particularly at what is called the Junction, just above the point where the Glacier des Bossons and the Glacier de Taconnaz are divided by the Montagne de la Cote. Here some underlying irregularity of the rocks, deep beneath the surface of the mighty river of ice, causes the formation of a labyrinth of fissures and crevasses, overhung with towering séracs, or ice turrets; and the ice descends between the Grands Mulets and the rock wall in front of the Gros Bechat in a sort of motionless cascade--motionless, that is to say, except when cracks break apart into yawning chasms, and massive blocks tumble into the depths. Even a practised climber is occasionally compelled to look to his steps in passing the Junction. On my return I witnessed an accident in this place which proved at the same time the reality of the danger and the usefulness in sudden crises of the mountaineer's rope. A tourist descending from the Grands Mulets was passing, under an impending sérac, around the head of a crevasse, where the only footway was a few inches of ice hewn with the axe. Being heedless or nervous, his feet shot from under him, and with a yell he plunged into the pit. Luckily, he was tied to the rope between two guides, one of whom had passed the dangerous corner, while the other, behind, had also a safe footing. As he fell the guides braced themselves, the rope zipped, and the unfortunate adventurer hung clutching and kicking at the polished blue wall. He had really descended but a few feet into the crevasse, though to him doubtless it seemed a hundred, and with a surprising display of strength, or skill, the guides hauled him out by simply tightening the rope. One of them pulled back and the other forward, and between them the sprawling victim rose with the strain to the brink of the chasm, where a third man dexterously caught and landed him. [Illustration: REFUGE STATION AT THE GRANDS MULETS, MONT BLANC.] Madame Marke and Olivier Gay were not so fortunate near this spot in 1870. A bridge of snow spanning a crevasse gave way beneath them, and, the rope breaking, they disappeared and perished in the abyss.