A Week among the Glaciers. 287 



day's sun, and any cause which should produce a slight vibration 

 of the air, would dislodge other masses above it, which were less 

 firmly fixed than even this one, and they would set the whole mass 

 to tumbling headlong down. This being spoken with so much 

 earnestness, and in a mere whisper, I proceeded. Our valet de 

 place, whom we had taken with us, was immediately before me, 

 and being rather awkward, moved very slowly, and had already 

 made one or two faise steps, which my guide seeing, advanced 

 at once and stopped him, then told me to pass him, as a few more 

 such steps might set some of the smaller blocks in motion, and 

 as we were behind, we should lose our lives, by his stupidity. 

 I passed him, and a few minutes' walk carried us to the opposite 

 side of this dangerous pass, where we sat down to rest and viewed 

 from a point of safety the danger which we had almost uncon- 

 sciously braved. It was now frightful to see other promontories 

 of ice, which while we were crossing had been hidden from our 

 view, resting upon mere feathery edges, with sheets of snow 

 dropping over their edges in festoons, appearing scarcely thick 

 enough to support their own weight. 



Our guides told us we could now prove, or rather test, the 

 truth of their assertions respecting the powerful effect of the 

 vibration of the air at this height, which hint we at once availed 

 ourselves of, by ordering the whole company to give three shouts, 

 at the height of their voices, which they did, and the effect of 

 which was quickly visible. The first shout produced no sensi- 

 ble movement, but with the second, though the sound produced 

 none of that sharp echo, which we often hear in the gorges of 

 the mountain valleys, yet its effect was manifest, first upon those 

 festooned edges of snow which I have mentioned above, and 

 which with another loud shout began to detach themselves in 

 quick succession, falling in considerable sheets, till one of no 

 great size fell some eighty feet, upon one of those huge rocks of 

 ice, which was poised so equally that it required but the slightest 

 force to turn the balance, when this slid from its resting place, 

 with but little velocity, not as fast apparently as a man would 

 walk ; but the momentum of so large a mass must have been 

 enormous. I should judge its slide was not more than twelve or 

 fifteen feet (though it may have been many more) when being 

 suddenly checked, by its base coming in contact with another 

 mass, the momentum it had acquired in its slide threw its sum- 



