Part 11 (1/2)
The Captain, being a blunt honest, straightforward man, could not understand this state of matters, and fell into a fit of abstracted perplexity on the sofa beside Mrs Stoutley, who listened listlessly to the Russian Professor as he attempted to explain to her and Emma the nature of a glacier.
”Well, I don't understand it at all,” said Mrs Stoutley, at the end of one of the Professor's most lucid expositions.
We may remark, in pa.s.sing, that the Professor, like many of his countrymen, was a good linguist and spoke English well.
”Not understand it!” he exclaimed, with a slight elevation of his eyebrows. ”My dear madam, it is most plain, but I fear my want of good English does render me not quite intelligible.”
”Your English is excellent,” replied Mrs Stoutley, with a smile, ”but I fear that my brain is not a sufficiently clear one on such matters, for I confess that I cannot understand it. Can you, Captain Wopper?”
”Certainly not, ma'am,” answered the Captain, thinking of the fickle Lawrence; ”it takes the wind out of my sails entirely.”
”Indeed!” said the Professor. ”Well, do permit me to try again. You understand that all the mountain-tops and elevated plateaus, for many miles around here, are covered with ice and snow.”
”Oh!” exclaimed the Captain, awaking to the fact that his answer was not relevant; ”may I ax what is the particular pint that puzzles you, ma'am?”
Emma laughed aloud at this, and coughed a little to conceal the fact.
She was rather easily taken by surprise with pa.s.sing touches of the ludicrous, and had not yet acquired the habit of effectually suppressing little explosions of undertoned mirth.
”The thing that puzzles me,” said Mrs Stoutley, ”is, that glaciers should _flow_, as I am told they do, and yet that they should be as hard and brittle as gla.s.s.”
”Ah, well, yes, just so, h'm!” said the Captain, looking very wise; ”that is exactly the pint that I want to know myself; for no man who looks at the great tongue of that glacier day Bossung--”
”Des Bossons,” said the Professor, with a bland smile.
”Day Bossong,” repeated the Captain, ”can deny that it is marked with all the lines, and waves, an eddies of a rollin' river, an' yet as little can they deny that it seems as hard-and-fast as the rock of Gibraltar.”
The Professor nodded approvingly.
”You are right, Captain Whipper--”
”Wopper,” said the Captain, with a grave nod.
”Wopper,” repeated the Professor, ”the glacier des Bossons, like all the other glaciers, seems to remain immovable, though in reality it flows-- ever flows--downward; but its motion is so slow, that it is not perceptible to the naked eye. Similarly, the hour-hand of a watch is to appearance motionless. Do you want proof? Mark it just now; look again in quarter of an hour, and you see that it has moved. You are convinced. It is so with the glacier. Mark him to-day, go back to-morrow--the mark has changed. Some glaciers flow at the rate of two and three feet in the twenty-four hours.”
”Yes, but _how_ do they flow, being so brittle?” demanded Mrs Stoutley.
”Ay, that's the pint, Professor,” said the Captain, nodding, ”_how_ do they flow, bein' made of hard and brittle ice?”
”Why, by rolling higgledy-piggledy over itself of course,” said Lewis, flippantly, as he came up and sat down on the end of the sofa, being out of humour with himself and everybody in consequence of having utterly failed to gain the attention of Nita h.o.r.etzki, although he had made unusually earnest efforts to join in conversation with her father.
Owing to somewhat similar feelings, the artist had flung himself into a chair, and sat glaring at the black fireplace with a degree of concentration that ought to have lighted the firewood therein.
”The cause of a glacier flowing,” said the Professor, ”has long been a disputed point. Some men of science have held that it is the pressure of ice and snow behind it which causes it to flow. They do not think that it flows like water, but say it is forced from behind, and crushed through gorges and down valleys, as it were, unwillingly. They say that, if left alone, as they now are, without additions, from this time forward, glaciers would no longer move; they would rest, and slowly melt away; that their motion is due to the fact that there are miles and miles of snow-fields, thousands of feet deep, on the mountain-tops and in the gorges, to which fresh snows are added every winter, so that the weight of what is behind, slipping off the slopes and falling from the cliffs, crushes down and forward that which is below; thus glaciers cannot choose but advance.”
”Ay, ay,” said the Captain, ”no doubt no doubt that may be so; but why is it that, bein' as brittle as gla.s.s, a glacier don't come rumblin' and clatterin' down the valleys in small hard bits, like ten thousand millions of smashed-up chandeliers?”
”Ay, there's the rub,” exclaimed Lewis; ”what say you to that?”
”Ha!” exclaimed the Professor, again smiling blandly, ”there you have touched what once was, and, to some philosophers it seems, still is, the great difficulty. By some great men it has been held that glacier ice is always in a partially soft, viscid, or semi-fluid condition, somewhat like pitch, so that, although _apparently_ a solid, brittle, and rigid body, it flows sluggishly in reality. Other philosophers have denied this theory, insisting that the ice of glaciers is _not_ like pitch, but like gla.s.s, and that it cannot be squeezed without being broken, nor drawn without being cracked. These philosophers have discovered that when ice is subjected to great pressure it melts, and that, when the pressure is removed, the part so melted immediately freezes again--hence the name regelation, or re-freezing, is given to the process. Thus a glacier, they say, is in many places being continually melted and continually and instantaneously re-frozen, so that it is made to pa.s.s through narrow gorges, and to open out again when the enormous pressure has been removed. But this theory of regelation, although unquestionably true, and although it exercises _some_ influence on glacier motion, does not, in my opinion, alone account for it. The opinion which seems to be most in favour among learned men--and that which I myself hold firmly--is, the theory of the Scottish Professor Forbes, namely, that a glacier is a semi-fluid body, it is largely impregnated throughout its extent with water, its particles move round and past each other--in other words, it flows in precisely the same manner as water, the only difference being that it is not quite so fluid; it is sluggish in its flow, but it certainly models itself to the ground over which it is forced by its own gravity, and it is only rent or broken into fragments when it is compelled to turn sharp angles, or to pa.s.s over steep convex slopes. Forbes, by his careful measurements and investigations, proved incontestably that in some glaciers the central portion travelled down its valley at double or treble the rate of its sides, without the continuity of the ma.s.s being broken. In small ma.s.ses, indeed, glacier-ice is to all appearance rigid, but on a large scale it is unquestionably ductile.”