1. Next day the children asked their mother to tell them what coal really was. Harry did not think it was a stone, because he had broken two or three lumps with a hammer. He found that it broke much more easily than stone.

2. Besides, it did not fly all into sharp bits, but came off in slices; and he saw that it had straight lines along it. When he poked his knife in between these lines, he could take off a slice of coal at once!

3. Dora did not think it was a metal, because she had learnt that iron would melt in a fire and flow like water. 'Coal does not melt,' she said, 'every one knows that!'

4. She took a small lump out of the coal-box, and Harry did the same. Mother then fetched some pictures, and one or two other things, and the talk began.

5. 'It is no wonder that you can't guess what coal is! It does not look at all like what it was at first. It was not always in the ground; it used to live on the top and get the air and sunshine.'

6. 'It must have been alive,' said Harry. 'Was it an animal?'

'No.'

'Then it was a plant!' cried Dora.

7. 'Well, it is all that is left of many plants and trees, whole forests of plants and trees, that grew long, long ago.'

'Before you were born, mother?'

8. 'Yes, long before that! It was hundreds and thousands of years ago. It was so far back that the trees were not like the trees we have now. Many of them were big ferns. Think of a fern grown up to be a tree! And many were great horse-tails. You know what a horse-tail is?'

9. 'Oh yes,' said Dora, 'we find them in the ditch down the lane. It is such fun pulling them to pieces and putting them together again—like puzzles!'

10. 'Those trees must have been very strange,' said Harry. 'They would not be nice to climb. But there were no boys in those days, so it did not matter.'