_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.