ICE AND GLACIERS 231 



slight cracks in which a knife can scarcely be inserted? 

 becoming gradually enlarged to chasms, hundreds or evett 

 thousands, of feet in length, and twenty, fifty, and as much 

 as a hundred feet in breadth, while some of them are im- 

 measurably deep. Their vertical dark blue walls of crystal 

 ice, glistening with moisture from the trickling water, form 

 one of the most splendid spectacles which nature can present 

 to us ; but, at the same time, a spectacle strongly impregnated 

 with the excitement of danger, and only enjoyable by the 

 traveller who feels perfectly free from the slightest tendency 

 to giddiness. The tourist must know how, with the aid of well- 

 nailed shoes and a pointed Alpenstock, to stand even on 

 slippery ice, and at the edge of a vertical precipice the foot 

 of which is lost in the darkness of night, and at an unknown 

 depth. Such crevasses cannot always be evaded in crossing 

 the glacier; at the lower part of the Mer de Glace, for 

 instance, where it is usually crossed by travellers, we are 

 compelled to travel along some extent of precipitous banks 

 of ice which are occasionally only four to six feet in 

 breadth, and on each side of which is such a blue abyss. 

 Many a traveller, who has crept along the steep rocky 

 slopes without fear, there feels his heart sink, and cannot 

 turn his eyes from the yawning chasm, for he must first 

 carefully select every step for his feet. And yet these blue 

 chasms, which lie open and exposed in the daylight, are by 

 no means the worst dangers of the glacier; though, indeed, 

 we are so organised that a danger which we perceive, and 

 which therefore we can safely avoid, frightens us far more 

 than one which we know to exist, but which is veiled from 

 our eyes. So also it is with glacier chasms. In the lower 

 part of the glacier they yawn before us, threatening death 

 and destruction, and lead us, timidly collecting all our pres- 

 ence of mind, to shrink from them; thus accidents seldom 

 occur. On the upper part of the glacier, on the contrary, 

 the surface is covered with snow; this, when it falls thickly, 

 soon arches over the narrower crevasses of a breadth of 

 from four to eight feet, and forms bridges which quite con- 

 ceal the crevasse, so that the traveller only sees a beautiful 

 plane snow surface before him. If the snow bridges are thick 

 enough, they will support a man; but they are not always 



