of them close to it, and fewer of them farther off, till they are piled
up in a ring round it, just as the sand is piled up round a beetle's
burrow. For days, and weeks, and months this goes on; even it may be for
hundreds of years: till a great cone is formed round the steam vent,
hundreds or thousands of feet in height, of dust and stones, and of
cinders likewise. For recollect, that when the steam has blown away the
cold earth and rock near the surface of the ground, it begins blowing out
the hot rocks down below, red-hot, white-hot, and at last actually
melted. But these, as they are hurled into the cool air above, become
ashes, cinders, and blocks of stone again, making the hill on which they
fall bigger and bigger continually. And thus does wise Madam How stand
in no need of bricklayers, but makes her chimneys build themselves.

And why is the mouth of the chimney called a crater?

Crater, as you know, is Greek for a cup. And the mouth of these
chimneys, when they have become choked and stopped working, are often
just the shape of a cup, or (as the Germans call them) kessels, which
means kettles, or caldrons. I have seen some of them as beautifully and
exactly rounded as if a cunning engineer had planned them, and had them
dug out with the spade. At first, of course, their sides and bottom are
nothing but loose stones, cinders, slag, ashes, such as would be thrown
out of a furnace. But Madam How, who, whenever she makes an ugly
desolate place, always tries to cover over its ugliness, and set
something green to grow over it, and make it pretty once more, does so
often and often by her worn-out craters. I have seen them covered with
short sweet turf, like so many chalk downs. I have seen them, too,
filled with bushes, which held woodcocks and wild boars. 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