precipices.  Arrived at this stage of one hundred and sixty feet below the surface of the glacier, he peered through the twilight dimness and perceived that the chasm took another turn and stretched away at a steep slant to unknown deeps, for its course was lost in darkness.  What a place that was to be in—­especially if that leather belt should break!  The compression of the belt threatened to suffocate the intrepid fellow; he called to his friends to draw him up, but could not make them hear.  They still lowered him, deeper and deeper.  Then he jerked his third cord as vigorously as he could; his friends understood, and dragged him out of those icy jaws of death.

Then they attached a bottle to a cord and sent it down two hundred feet, but it found no bottom.  It came up covered with congelations—­evidence enough that even if the poor porter reached the bottom with unbroken bones, a swift death from cold was sure, anyway.

A glacier is a stupendous, ever-progressing, resistless plow.  It pushes ahead of its masses of boulders which are packed together, and they stretch across the gorge, right in front of it, like a long grave or a long, sharp roof.  This is called a moraine.  It also shoves out a moraine along each side of its course.

Imposing as the modern glaciers are, they are not so huge as were some that once existed.  For instance, Mr. Whymper says: 

“At some very remote period the Valley of Aosta was occupied by a vast glacier, which flowed down its entire length from Mont Blanc to the plain of Piedmont, remained stationary, or nearly so, at its mouth for many centuries, and deposited there enormous masses of debris.  The length of this glacier exceeded eighty miles, and it drained a basin twenty-five to thirty-five miles across, bounded by the highest mountains in the Alps.  The great peaks rose several thousand feet above the glaciers, and then, as now, shattered by sun and frost, poured down their showers of rocks and stones, in witness of which there are the immense piles of angular fragments that constitute the moraines of Ivrea.

“The moraines around Ivrea are of extraordinary dimensions.  That which was on the left bank of the glacier is about thirteen miles long, and in some places rises to a height of two thousand one hundred and thirty feet above the floor of the valley!  The terminal moraines (those which are pushed in front of the glaciers) cover something like twenty square miles of country.  At the mouth of the Valley of Aosta, the thickness of the glacier must have been at least two thousand feet, and its width, at that part, five miles and A quarter.”

It is not easy to get at a comprehension of a mass of ice like that.  If one could cleave off the butt end of such a glacier—­an oblong block two or three miles wide by five and a quarter long and two thousand feet thick —­he could completely hide the city of New York under it, and Trinity steeple would only stick up into it relatively as far as a shingle-nail would stick up into the bottom of a Saratoga trunk.