"It would not be comfortable," replied Mary; "besides, it is not nearly as warm as here. Poor Uncle Robert would nearly freeze during the long winter. He would also find another surprise awaiting him if he went to Mars. Mars is a smaller world than the earth, so everything weighs less." "Ah! I see," said Harry, clapping his hands with glee. "Uncle would not be so heavy on Mars. How glad he would be to go there! Poor Uncle Robert! He is so heavy he just shakes the house when he walks across the floor. Next time I see him I shall say: 'Go to Mars, Uncle Robert, and see what will happen to you there.' How much would he weigh on Mars?" "He weighs two hundred and forty pounds here, and would weigh only ninety pounds there, and you would weigh only thirty pounds. So I could pick you up, couch and all, and carry you as easily as Nellie carries her doll in its doll-carriage." "Then dollie would weigh nothing at all," said Nellie, looking at her doll curiously. Harry looked puzzled, and after thinking a moment, he said to his sister: "I cannot see why I would weigh less if I went to Mars." [Illustration: MARS AND THE EARTH.] "Because the planet being smaller than the earth, it has less power to attract you and to hold you down to its surface. The earth is like a great magnet, and if there were not something drawing us to it and keeping us there, we would be greatly puzzled. Tables and chairs would not stand firm, and we would stagger about for want of weight, just as when a diver tries to walk in deep water. He has to have heavy weights fastened to him so as to keep him in place. A stone that would be quite heavy on earth would weigh only a few ounces on Mars. Nellie could carry this large rocking-chair I am sitting in and eight or ten dollies as well. Do you remember seeing the men at the circus jumping over bars five feet high? Well, on Mars they could jump fifteen feet, while the clumsy old elephant we saw there would probably be as graceful and nimble as a deer." "How would football be on Mars?" asked Harry. "Very unlike football here, dear. A good kick would send the ball much farther than here." "Is Mars very far away?" asked Nellie. "If we could go there in a train, would it take us ever so long going?" "About sixty years," said Mary, laughing, "if the train went a mile a minute. If you tried to walk it, going four miles an hour and ten hours a day, it would take you more than two thousand years to get there. So, I don't think we can take that trip, little girl, can we? But let us call on the next-door neighbor or neighbors to Mars, for there are about four hundred and fifty of them." STORY OF THE BABY PLANETS. "Four hundred and fifty little worlds?" asked Harry. "Where can there be room for them all, and don't they knock against each other in the sky?" "No, there is plenty of room for them up there. Besides, they are so small, some of them being only ten miles wide."