Once I came on a beautiful round crater on the top of a mountain, which was filled at the bottom with a splendid crop of potatoes.

Though Madam How had not put them there herself, she had at least taught the honest Germans to put them there.

And often Madam How turns her worn-out craters into beautiful lakes.

There are many such crater-lakes in Italy, as you will see if ever you go there; as you may see in English galleries painted by Wilson, a famous artist who died before you were born.

You recollect Lord Macaulay's ballad, "The Battle of the Lake Regillus"?
Then that Lake Regillus (if I recollect right) is one of these round crater lakes.
Many such deep clear blue lakes have I seen in the Eifel, in Germany; and many a curious plant have I picked on their shores, where once the steam blasted, and the earthquake roared, and the ash-clouds rushed up high into the heaven, and buried all the land around in dust, which is now fertile soil.