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What the beetle and the ant…lion do on a very little scale； the steam inside
the earth does on a great scale。 When once it has forced a vent into the
outside air； it tears out the rocks underground； grinds them small against
each other； often into the finest dust； and blasts them out of the hole which
it has made。 Some of them fall back into the hole； and are shot out again：
but most of them fall round the hole； most 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
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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 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
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in dust； which is now fertile soil。 And long did I puzzle to find out why
the water stood in some craters； while others； within a mile of them
perhaps； were perfectly dry。 That I never found out for myself。 But
learned men tell me that the ashes which fall back into the crater； if the
bottom of it be wet from rain； will sometimes 〃set〃 （as it is called） into a
hard cement； and so make the bottom of the great bowl waterproof； as if it
were made of earthenware。
But what gives the craters this cup…shape at first？
ThinkWhile the steam and stones are being blown out； the crater is
an open funnel； with more or less upright walls inside。 As the steam
grows weaker； fewer and fewer stones fall outside； and more and more fall
back again inside。 At last they quite choke up the bottom of the great
round hole。 Perhaps； too； the lava or melted rock underneath cools and
grows hard； and that chokes up the hole lower down。 Then； down from
the round edge of the crater the stones and cinders roll inward more and
more。 The rains wash them down； the wind blows them down。 They
roll to the middle； and meet each other； and stop。 And so gradually the
steep funnel becomes a round cup。 You may prove for yourself that it
must be so； if you will try。 Do you not know that if you dig a round hole
in the ground； and leave it to crumble in； it is sure to become cup… shaped
at last； though at first its sides may have been quite upright； like those of a
bucket？ If you do not know； get a trowel and make your little
experiment。
And now you ought to understand what 〃cone〃 and 〃crater〃 mean。 And
more； if you will think for yourself； you may guess what would come out
of a volcano when it broke out 〃in an eruption；〃 as it is usually called。
First； clouds of steam and dust （what you would call smoke）； then volleys
of stones； some cool； some burning hot； and at the last； because it lies
lowest of all； the melted rock itself； which is called lava。
And where would that come out？ At the top of the chimney？ At the
top of the cone？
No。 Madam How； as I told you； usually makes things make
themselves。 She has made the chimney of the furnace make itself； and
next she will make the furnace…door make itself。
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The melted lava rises in the craterthe funnel inside the cone but it
never gets to the top。 It is so enormously heavy that the sides of the cone
cannot bear its weight； and give way low down。 And then； through ashes
and cinders； the melted lava burrows out； twisting and twirling like an
enormous fiery earth…worm； till it gets to the air outside； and runs off
down the mountain in a stream of fire。