It was several days before Mary could see Harry again and tell him "sky-stories," as he called them, for he had been suffering much pain. Even her gentle voice irritated him, and perfect quiet was ordered by the doctor until the little sufferer was better. At last he was able to enjoy the sunlight and the flowers and the song of the birds again, and one bright morning he was all ready, as he told his sister, to take another trip to Starland. As Mary arranged the pillows on the couch for him, and a large sunshade, so that the glare of sunlight would not hurt his eyes, he caught hold of her hand and, pressing it lovingly, he said:

"Darling, what should I do without you? You are so good to me."

"How can I help it, little sweetheart!" said Mary, as she turned her head aside to keep him from seeing the tears that would come to her eyes; "how can I help it, when I love you so dearly. Besides, you are my own dear little brother, and you don't know how I missed you all last week."

"Did you really, sister? And I was dreaming away all day long about the wonderful stories you have been telling me. I played football on Mars, and had beautiful wings when I lived on the baby planets, and flew from one to another, and now I want to know something about the giant planets. You said they lived next door to the little tiny planets."

STORY OF JUPITER.

"Yes, next door to the baby planets we come to the largest of all, the giant planet Jupiter. If a tunnel were made through the center of Jupiter, eleven globes as large as the earth, placed side by side, would reach from one side to the other. You could make thirteen hundred globes out of planet Jupiter as large as the earth. If the earth were a large snowball, and a giant could roll thirteen hundred such snowballs into one, he would have a ball to play with as large as planet Jupiter. If it were made of the same material as the earth, it would be more than three hundred times as heavy."

"It would take a very big giant to play with that snowball, wouldn't it?" said Harry, smiling at the thought. "There would not be much room in the sky for him to play in, would there?"

"Plenty of room," replied his sister, laughing; "room for millions and millions of balls as large as Jupiter, and much, much larger."

"What a wonderful place the sky must be!" said Harry, in awe. "Now, tell me some more about Jupiter. Didn't you tell me last week that he is hidden away among blankets, and very, very hot?"

"That is right, Harry, but some day he will cool down, and the blankets will change into beautiful oceans and seas and lakes. Then it will be a world like ours, with trees and flowers, and perhaps people will live there."

"The sun is so much further away from Jupiter than from the earth that it gives it only one twenty-seventh as much light and heat. If you can imagine the sun as a bright lamp in the sky, and someone turning down the wick of the lamp till its light is only one twenty-seventh as bright as it is now, you can imagine how dim the light and small the amount of heat must be on Jupiter."

"How long does Jupiter take in going round the sun?" asked Harry.

"About twelve years," replied Mary; "and the day is only about ten hours long, instead of twenty-four as here."

"What a short day!" said Harry, in surprise. "Then you could work only five hours and sleep five hours. I believe I would sleep all day, and all night, too. I must tell Nellie about that next time I see her."

"Why did not she come this morning, I wonder?" said Mary. "Perhaps she has gone for a walk with her nurse."

"I'll tell her about my trip," said Harry generously, "when she comes over here again. And now what else is there about Jupiter?"

JUPITER AS SEEN THROUGH A TELESCOPE.

"If you look at it through a large telescope you will see that it is beautifully colored, as if Uncle Robert had taken his paint-box, and dipped his brush into browns and reds, and tinted the cloud-belts around Jupiter here and there with touches of yellow and orange, olive-green and purple. Only an artist could get such beautiful effects. If we could journey to one of the little moons of Jupiter——"

"Has Jupiter moons also?" asked Harry, delighted at the thought.

"Five of them," said Mary; "and I shall tell you about them later. Supposing we could journey to one of these little moons, what a glorious sight Jupiter would be! From the nearest moon it would look thousands of times larger than our moon. The colors we see only faintly through our telescopes would present a magnificent sight when seen at close range, while constant changes would be taking place, as varied as the changes in the clouds flitting across a summer sky. Great cloud-masses drift hither and thither with enormous speed, driven by winds of hurricane force. By watching the changes that take place in the clouds, we know there must be winds blowing at the rate of nearly two hundred miles per hour. Do you remember the cyclone Uncle Robert told us about, when several houses were blown down and trees uprooted?"

"Yes, indeed, I do," replied Harry, "and his poor little dog Fido was nearly killed by a falling chimney."

"Poor little Fido would not have much chance on Jupiter. The storms there are ever so much worse than here. The strongest buildings would be blown down in a few moments; sturdy oaks would be uprooted and blown about by the wind like straws."

"Do the storms last very long?" asked Harry.

"They last six and seven weeks at a time," replied Mary, "so that Jupiter would scarcely be a comfortable world to live on yet. Besides, it is still in the fiery stage."

"Won't you tell me some more about the little moons of Jupiter?" asked Harry.

THE MOONS OF JUPITER.

"They are not so little, after all, brother, except the first one, which is only one hundred miles wide. It is such a shy little moon that it keeps hiding behind Jupiter, or gets so close to him that it is lost in the glare of light from the giant planet. We had no idea it was there at all until an American astronomer, Professor Barnard, caught sight of it one evening. It was playing hide-and-seek as usual, but Professor Barnard, with his keen eyes, spied the little speck of light. It is now known as the fifth moon of Jupiter. It was only discovered in 1892, and just think, that for the hundreds and hundreds of years it has been there, yet no one had seen it. The French people were so delighted because Professor Barnard caught sight of the little truant that they gave him a beautiful gold medal."

"Won't you show the little moon to me sometime?" said Harry. "I should like to see it so much."

"You can only see it through a very large telescope; but I can show you the other four moons if Uncle Robert will lend us his telescope."

"Here he comes," said Harry, in great glee, as he saw Uncle Robert crossing the meadow. "Won't you bring over your telescope this evening?" said Harry pleadingly, as he told him what Mary had just said.

"Certainly, my little man," his uncle replied; "but we can only see three of the moons this evening as one of them is eclipsed."

"What's that?" said Harry, in surprise at the strange word.

"Eclipsed means hidden," said Mary, laughing. "If Uncle Robert stands right in front of you, as he is doing just now, he hides me from you, so I am eclipsed."

"Very true," said Uncle Robert, laughing heartily at the hint. "Planet Mary is eclipsed by Uncle Robert, and poor little Planet Harry cannot see her till Uncle Robert gets out of the way." This he immediately proceeded to do, and next moment he was pursuing Fido, who was having a not over-friendly encounter with a strange cat in a neighbor's garden.

"Oh, dear," said Harry, in distress, "where were we? We were up in the sky among the planets, and now Uncle Robert has brought us back again to earth. Do listen to poor Fido." He certainly seemed to be getting the worse of the encounter with Pussy; but when Uncle Robert came to the rescue the enemy vanished, and Fido, nothing daunted, went in search of other prey. When peace and quiet were once more restored, Mary resumed her story.

ECLIPSE OF JUPITER'S MOONS.

"Do you know, the appearance and disappearance of the little moons of Jupiter once gave a great deal of trouble to astronomers. They had a way of appearing a little too soon or a little too late. They were very seldom on time. This was very provoking, as astronomers were rather proud of being able to tell exactly when these little moons could be seen. At last they found out what was the matter, and that they were to blame and not the moons. We see the little moons on account of their light, and light takes time to travel. Don't you remember, I told you sound travels a mile in five seconds. Light travels even more quickly, for it only takes a little over a second in coming to us from the moon. It takes about eight minutes in coming to us from the sun; but Jupiter is about five times as far away from us as the sun, so that light takes about half an hour in coming to us from Jupiter. We do not see it as it is, but as it was more than half an hour ago, when its rays of light started out to Planet Earth.

"Now, Jupiter, in going around the sun, is sometimes on the same side of the sun as we are. Then the light from the moons reaches us in about thirty-two minutes. But when Jupiter is on the opposite side of the sun, and as far away from us as it can be, then light takes as much as forty-eight minutes in coming here—over a quarter of an hour longer. So a clever astronomer decided that when Jupiter and his moons are nearest to us, it does not take as long for their light to reach us as when they are farther away, and this is because light, like sound, must have time to travel.

"Even though light can go round the earth seven times in a second, traveling at the rate of about 186,000 miles a second, yet, as Jupiter is millions of miles away, it takes light about half an hour, and some times forty-eight minutes, for it to cross that great distance. It is just the same as if Uncle Robert were in India. It would take him a much longer time to come and see you than if he were at his home just a few hundred yards away. It takes time for him to travel here, just as it takes time for light to travel from the little moons of Jupiter."

"I wish we had five moons shining on our earth," said Harry; "how pretty it would be! Does it take the moons as long as our moon to get around Jupiter?"

"They are much livelier than our moon," replied Mary; "and the second moon flies right around Jupiter in a little more than a day and a half, and even the outside moon only takes about two weeks; so there must always be a moon shining in the sky for Jupiter. These moons, except the moon discovered by Professor Barnard, are all larger than our moon, and the fourth one is nearly as large as Mars. But I hear the bell for lunch, Harry, and I must run away now. I will tell you about the other planets later."

"How many are there?" said Harry, as his sister kissed him good-by.

"Only three," replied Mary; "and I shall tell you about them to-morrow, if you are not too tired."

"Too tired!" said Harry. "I am never too tired to listen to you."

JUPITER.

Oh! that it were my doom to be

The spirit of yon beauteous star,

Dwelling up there in purity,

Alone, as all such bright things are;

My sole employ to pray and shine,

To light my censer at the sun!