A few evenings later Mary had a wonderful story to tell her brother about some visitors from space who often visit the kingdom of Giant Sun. "They are called comets, or hairy stars, but I rather enjoy calling them 'celestial tramps.'"

"What are they like?" asked Harry.

STORY OF COMETS.

"They usually have a bright golden head, sometimes as large as the earth, and as they approach the sun they adorn themselves with a glittering train millions of miles in length. Some of the comets are regular visitors, and we know just when to expect them; others come, and do not return for hundreds of years, while a few visit the sun never to return again."

"Where do they come from?" asked Harry.

"We scarcely know," replied Mary, "except that it is from outer space, just like tramps on earth. We do not know where tramps come from, nor do we expect to see them again. If they do revisit us, however, we can usually recognize them. Do you remember the old man who came to the kitchen door the other day and begged for food? You felt so sorry for him. You would know him if you saw him again on account of his long white beard, white hair, and shabby clothes.

"When a celestial tramp returns, however, it is not so easy to recognize it. When it first greeted us it may have had a large head and a gorgeous train millions of miles in length. Next time we see it, how it has changed! Its head may be small, its train may have vanished, or it may be the proud owner of three or four trains. A comet usually changes its appearance at every visit. Just as if the old man we saw the other day were to cut off his beard, dye his hair black, and wear Uncle Robert's dress-suit. We should not know him, should we, Harry?"

"I should think not," said Harry, laughing at the very idea. "Then how can you tell when the same comet visits us again?"

"Because it has a regular path marked out for it in the sky," replied Mary, "and it travels along that path unless something happens to it on the way. It may go too near giant planet Jupiter. Just like our tramp again. Let us suppose he has a regular path marked out and it takes him across Uncle Robert's farm and leads to our kitchen door. We may expect to see Mr. Tramp to-morrow, but as he crosses the farm a dog bites him and frightens him away. Perhaps then we may not see him again."

"Poor old man," laughed Harry. "I hope that won't happen to him. Do the 'celestial tramps' travel very quickly through the sky?"

"Not very quickly until they come close to the sun. Then they rush around it ever so much faster than an express train; but as they recede from the sun they go more slowly until they seem only to creep along, as if worn out by their long journey. They also lose their trains after they go away from the sun, and the train becomes shorter and shorter, till the comet looks like a round, fluffy ball, just as it did before it came too near the sun. It is the sun's heat that drives the particles from the head of the comet and forms a train."

"What are comets made of?" asked Harry.

"Of millions of tiny little particles covered with coats of glowing gas. These particles are made up of carbon, sodium, iron, and magnesium. You will find plenty of sodium in the sea, while common table salt is partly sodium. You know what magnesium is. Some of that medicine doctor gives you is made of it."

"So if I get some iron and salt and coal and some of my medicine, and put them all together, I should have a bit of a comet," said Harry.

"But you must remember the coal, iron, sodium, and magnesium must be very much heated, and don't forget the coat of gas. Sometimes a comet breaks into pieces, and the fragments travel along by themselves as meteors."

"Sometimes the earth plunges through swarms of meteors, which journey in regular paths around the sun. At such a time, the bright masses seem to fall in showers from the sky. There are three great showers which we always know when to expect. Some come in August, some on the 13th or 14th of November, and there is another shower which always appears within a day or two of the 27th of November.

STORY OF METEORS.

"What are meteors?" asked Harry.

"Meteors are great masses of stone or iron which sometimes weigh several tons. Lieutenant Peary found one not long ago in the Arctic regions, and it weighed about eighty tons. It is lucky for us that many meteors do not fall on the earth, or we should have to walk about with iron umbrellas over our heads as a protection. When they do fall on earth, they are much prized and placed in our museums as curiosities.

"A story is told about a meteor that fell on a farm some time ago. The landlord said it belonged to him, for when he rented the farm to the tenant he claimed all minerals and metals found in the ground.

"'But it was not on the farm when the lease was made out,' said the tenant.

"'Then I claim it as flying game,' replied the landlord angrily.

"'But it has neither wings nor feathers, so I lay claim to it as ground game,' said the tenant in reply.

"While the dispute was going on the custom-house officers seized the meteorite, because, as they said, it had come into the country without paying duty."

"That is not a true story, is it?" asked Harry, laughing.

"Scarcely," replied Mary; "but it was a good joke on the landlord. And now we come to the very smallest members of the family of Giant Sun. I mean the shooting stars."

"Those bright little flying stars we can see at night?" asked Harry.

STORY OF A SHOOTING STAR.

"Yes," replied Mary; "and if they could only talk, what a wonderful story they would have to tell! A shooting star is very much smaller than a meteor, and the largest does not weigh more than a quarter of an ounce. You could easily hold one in your hand, for it is like a small stone, only, unlike a stone, it is always on the move. It hurries along through space ever so much faster than an express train, and all goes well as long as it keeps above the blanket of air that surrounds the earth. If it comes too near, however, it is sure to be destroyed. It dashes into the air at the rate of twenty-five miles a second, rubbing against every particle it meets on its way. This makes it intensely hot, until it glows with brilliant light. We see it for a few moments as it flashes out against the dark sky; but the light soon fades and all that remains of the shooting star is its ashes. Sometimes they sift down upon the earth and settle on the tops of high mountains, or sink into the ocean, or float in through an open window and rest upon tables and books as fine dust. But when our good housekeeper finds it there she carefully removes it with her duster. She does not know nor does she care where it came from; it certainly has no right there, and she treats it with small ceremony."

"I wonder what she would say if she knew that the dust had come from the sky," said Harry.

"I do not think it would make any difference," said Mary, laughing. "And now I am going to tell you a little story about a shooting star, and then I must say good-night.

"It is said that the evil genii—you remember reading about them in the Arabian Nights, don't you, Harry?"

"Indeed I do," he replied.

"Well, at night they are said to fly up to the gates of heaven and listen to the conversation of the angels. When the angels see their hidden foes, they hurl fiery shooting stars at them and with so good an aim that for every shooting star we may be sure there is one spirit of evil less in the world."

STARLIGHT AT SEA.