"They are immense accumulations of ice, Mivins, that have been formed by the freezings and meltings of the snows of hundreds of years.

They cover the mountains of Norway and Switzerland, and many other places in this world, for miles and miles in extent, and sometimes they flow down and fill up whole valleys.

I once saw one in Norway that filled up a valley eight miles long, two miles broad, and seven or eight' hundred feet deep; and that was only a wee bit of it, for I was told by men who had travelled over it that it covered the mountains of the interior, and made them a level field of ice, with a surface like rough, hard snow, for more than twenty miles in extent." "You don't say so, sir!" said Mivins in surprise.

"And don't they _never_ melt ?" "No, never.

What they lose in summer they more than gain in winter.
Moreover, they are always in motion; but they move so slow that you may look at them ever so closely and so long, you'll not be able to observe the motion--just like the hour hand of a watch--but we know it by observing the changes from year to year.