_The same subject, continued._
_Mother._ Did you ever see a person rub his hands together, when he was
cold?
_Daughter._ O yes, mother, a great many times. I have seen father come
in from the cold, and rub his hands together, and afterwards hold them
to the fire and rub them again, and then they get warm.
_Mother._ And now, Caroline, take your hand and rub it quickly backwards
and forwards, over that woolen table-cloth, on the table in the corner
of the room, and tell me whether that will make your hand warm.
_Daughter._ O, yes, dear mother; I feel it grow warmer, the faster I rub
it.
_Mother._ Here are two small pieces of wood. Touch them to your cheek,
and tell me whether they feel warm now.
_Daughter._ They do not feel warm, nor cold, mother.
_Mother._ Now rub them together quickly a little while, and then touch
them to your cheek.
[Illustration: R]
_Daughter._ O, dear, mother! they are so hot that they almost burnt my
cheek.
_Mother._ Yes, Caroline; and do you not recollect, when you read
Robinson Crusoe, that his man Friday made a fire by rubbing two pieces
of wood together?
_Daughter._ O, yes, dear mother; and I have often wondered why Alice
could not light her lire and the lamp in the same manner, without those
matches, which have so offensive a smell.
_Mother._ It is very hard work, my dear, to obtain fire by rubbing two
pieces of wood together; and it would take too long a time to do it. The
two pieces of wood would grow warm by a very little rubbing; but in
order to make them take fire, they must be rubbed together a great
while.
_Daughter._ But, mother, if it takes so long a time to get fire by
rubbing two pieces of wood together, why can Alice set the match on fire
so easily by rubbing it once on the sand-paper?
_Mother._ That is what I am about to explain to you, my dear. Here, take
this piece of paper and hold it up to the lamp.
_Daughter._ It has taken fire, mother.
[Illustration: L]
_Mother._ Now take this piece of pine wood, and hold that up to the lamp
in the same manner, and see whether that will take fire too.
_Daughter._ Yes, mother, it has taken fire; but I had to hold it up to
the lamp much longer than I did the paper.
_Mother._ Now take this piece of hard wood, and do the same with that.
_Daughter._ The hard wood takes longer still to catch fire, mother.
_Mother._ Yes, my child. And now I am going to make the hard wood take
fire more quickly than the paper did.
_Daughter._ Dear mother, how can you do it?
_Mother._ I am going to show you, my dear. Here is a small phial, which
contains something that looks like water. It is spirits of turpentine. I
shall dip the point of the piece of hard wood into the phial, and take
up a little of the spirits of turpentine. Now, Caroline, touch the point
of the hard wood with the turpentine on it to the flame.
_Daughter._ Why, mother, it caught fire as soon as I touched the flame
with it!
_Mother._ Yes, certainly; and you now see that some things, like the
spirits of turpentine and the paper, take fire very readily, and others
take fire with more difficulty.
_Daughter._ Yes, mother; but when Alice drew the match across the
sand-paper, there was no flame nor fire to touch it to. How, then, could
it take fire?
_Mother._ Hold this piece of paper up to the blaze of the lamp, my dear,
but be careful not to touch the fire or flame of the lamp; only hold it
close to the blaze.
_Daughter._ Why, mother, it has taken fire!
_Mother._ You see, then, that a thing will sometimes take fire when it
does not touch the fire.
_Daughter._ Yes, mother; but I do not understand where the fire comes
from.
_Mother._ The fire comes from the heat, my dear. Now, you know that heat
is produced by rubbing two things together; and that some things, like
the spirits of turpentine, take fire very easily, or with very little
heat; and others, like the hard wood, require to be heated some
time,--or, in other words, require much heat,--to make them take fire,
or to burn. Some things require only as much heat to make them take fire
as can be obtained by rubbing them together very quickly, like the wood
which Robinson Crusoe's man Friday used.
_Daughter._ But, mother, the match is made of wood,--why does that take
fire so easily?
_Mother._ It is true, Caroline, that the match is made of wood; but it
has something at the end of it, which takes fire much more easily than
the spirits of turpentine. Indeed, so easily does it take fire, that it
requires only so much heat to set it on fire as can be obtained by
drawing the match once across the sand-paper.
_Daughter._ But, mother, matches do not always take fire. I have seen
Alice rub several across the sand-paper, before she could set one on
fire.
_Mother._ That is true, and the reason of this is, that the matches are
not all well made. Now, if I should take several pieces of hard wood and
tie them together, and dip their ends into the spirits of turpentine,
what would happen, if the ends of some of the pieces did not touch the
spirits of turpentine, because I had not tied them together with their
points all even?
_Daughter._ Why, mother, some of them would take fire easily, because
the points had the spirits of turpentine on them; while those which did
not touch the spirits could not be lighted so easily.
_Mother._ So it is, my dear, with the matches. They are all dipped into
the substance which takes fire so easily; but some of the ends do not
reach the substance, and do not become coated with it, and therefore
they will not light more easily than the pine wood of which they are
made.