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Neptune, however, the density is less than that of water, and in Uranus only slightly greater.

The planet must also possess a suitable atmosphere. This is an all-important condition for the support of animal life—at least, for the existence of man and the higher orders of animals. This atmosphere must, so far as we know, consist of oxygen and nitrogen gases mechanically mixed in proper proportions, and with a small quantity of carbonic acid gas. Were the oxygen in smaller quantity than it exists in the earth's atmosphere, life could not be supported. On the other hand, were it much in excess of its present amount, a fever would be produced in the blood which would very soon put an end to animal life. The presence of other gases in excessive quantities would also render the air unfit for breathing. We see, therefore, that a comparatively slight change in the composition of a planet's atmosphere would, so far as our experience goes, render the planet uninhabitable by any of the higher forms of life with which we are familiar.

For the support of life on a planet, water is also absolutely necessary. Without this useful fluid the world would soon become a desert, and life and vegetation would speedily vanish from its surface.

Geological conditions must also be considered. It is clearly necessary for the welfare of human beings, at least, that the surface-soil should be suitable for vegetation, and that the rocks of the planet's crust should contain coal, iron, lime, and other minerals, substances almost indispensable for the ordinary wants of civilised existence.

That all or any of the conditions considered would be complied with in the case of a planet revolving round a star it is, of course, impossible to say. But when we find stars showing by their spectra that they contain chemical elements identical with those which exist in the sun and the earth, analogy would lead us to suppose that very possibly a planet resembling our earth may revolve round the distant sun. I say a planet, for evidently there would be only one distance from the central luminary-a distance depending on its size-at which the temperature necessary for the support of life would exist, as in the case of the earth, over the whole of the planet's surface. For other planets of the stellar system, life would be, if it existed at all, most probably confined to restricted regions of the planet's surface. There would, therefore, be in each system one planet,

and only one, especially suitable for the support of animal life as we know it. In the case of a star larger than the sun, the planet should be placed at a greater distance than the sun is from the earth, but in this case the length of the year and the seasons would be longer than ours.

The star which most nearly resembles the sun in the character of the light which it emits is the bright star Capella. Arcturus has a somewhat similar spectrum. But these are probably suns of enormous size, if any reliance is to be placed on measures of their distance. Other bright stars with spectra of the solar type are Pollux, Aldebaran, Beta Andromeda, Alpha Arietis, Alpha Cassiopeia, Alpha Cygni, and Alpha Ursa Majoris. Another star is Eta Herculis.. The magnitude of this star as measured with the photometer is about three and a half. A parallax found by Belopolsky and Wagner places it a distance of 515,660 times the sun's distance from the earth. Placed at this distance the sun would, I find, be reduced to a star of the third magnitude. This result would imply that Eta Herculis is a slightly smaller sun than ours; and a planet placed a little nearer to the star than the earth is to the sun might, perhaps, fulfil the conditions of a life-bearing world.

The number of stars visible in our largest telescopes is usually estimated at one hundred millions. Of these we may perhaps assume that ten millions have a spectrum of the solar type, and, therefore, closely resemble the sun in their chemical constitution. If we suppose that only one in ten of these is similar in size to the sun, and has a habitable planet revolving round it, we have a total of a million worlds fitted for the support of animal life.

We may, therefore, conclude with a high degree of probability that among the 'multitudinous' stellar hosts there are probably many stars having life-bearing planets revolving round them.



THE Glen of Cloy is a great glen. It widens out to the sea, and it narrows back to the mountains.

The sea comes in there from very far away; a smooth and whispering sea, not like the rough Moyle. For all the wild waves sink their heads far out at the horns of the bay; and they come in softly, and glide up the shore, most beautiful in the long curves just before they break. They fall on the beach with a little sound of laughter-they die gladly.

The sides of the glen are mountains. Their slopes are rocky, their heads are green; and on one mountain there stood a castle long ago. It was the castle of the Chief of Cloy. His name was Lara, and he was young; but a strong chief, nevertheless, was the Chief of Cloy, ages and ages ago.

One thing men remarked of him-that his luck was unbroken. For this young men envied Lara, and old men pitied him. For luck is good, said they; but it is better to have no luck than to have it unbroken.

Some thought that Lara's luck came of the friendship he held with the Fairy King of Tievara. That was a strange friendship between a fairy and the mortal; and none knew how it had begun. Only they said it was certain that Lara had rendered some service unwittingly to the fairy kingdom, and for this the Fairy King had made himself known, and offered friendship. The young Chief of Cloy was rash, and he accepted all. He believed in luck, and he feared neither fiend nor fairy.

When he spent long times away from his castle, and came back some day on a sudden, pale of face, and gay of speech, and weary, his men knew that he had been hunting with the Fairy King, and they asked him no questions. They thought that he had the charm of the fern-seed, by which he could walk at certain seasons invisible. They were sure he could hear the

fairy speech; for he would listen intently, and sometimes smile, when other men heard only the wind rustling in dry leaves, or water dropping from a rock.

Of one thing they were not sure, and that was whether the Fairy King had ever told his name to Lara-the name that no one knows.

In another glen there lived a poor and brave maiden, Ailish, the daughter of Oisin. She lived alone, and her beauty was a guard to her; as it happened in the days of old in Erin. The Chief of Cloy loved Ailish, and asked her to marry him. Three times she refused, and told him reasons. But he made light of them; and once again he asked her, and she consented. So they were betrothed. When the next moon was full, they would be married; and the heart of Lara was glad within him, while the heart of Ailish was thoughtful.

It happened then one summer evening that Lara was alone with the Fairy King, and all the fairy court had trooped away down the glen. They two sat by a deep pool, and the light was fading out of the sky. The silver birches made a flickering with their thin leaves in the air about them; but the alder kept its black shadow, and in the shadow of the alder they sat. Then Lara, in the openness of his heart, told his fairy friend that it wanted but three days to his wedding, and told him the name of his bride; for he put faith in him.

The Fairy King said little. And Lara told him of the beauty of Ailish; for his heart was true to her, and he had no suspicion. But he had better have kept silence.

'Is she as white as may on the thorn?' asked the Fairy. For he began to wonder about this bride.

'Not so white as may,' said Lara; 'but sweeter.'

'Are her eyes as blue as bluebells?' said the Fairy, wondering still.

'Not so blue,' said Lara again; 'but deeper.'

'Then she is not so fair as a flower?' cried the Fairy.

'Not so fair,' said Lara slowly; 'but dearer.'

After a while he explained. 'When mortals love each other, it is not as fairies choose flowers by moonlight. For we love, and leave not. Henceforth, though we have two lives, we have but one soul between us. This is what you will never understand, Fairy! You cannot, because you have no soul.'

The Fairy King sat silent, and swayed on his alder branch till his feet touched the water. He cast himself along it, and

gazed downwards with his glittering eyes.

Below all the shadows he could see the little brown fish sleeping under the stones, and he could count the sand at the bottom if he chose. But now he had a new desire. He wanted that beautiful bride And he sat in the alder shadow,

who would soon belong to Lara. and thought of it; long after Lara had left him, and was riding homewards down the Glen of Cloy.

The sun rose, and the sun set, and now it wanted but one night more before the wedding-day. Ailish, to-morrow's bride, stood alone in the door of her house; and the days that were past and the days that were to come seemed alike strange to her. But there was no one to whom she could tell how strange they were, for she lived alone.

No house was in sight of her low brown house. But two trees stood over it, one on the east side, and one on the west. The western tree was a great larch, which gathered darkness and shadows under the fringes of his long arms, and stretched them out like a wide web, dusky and grim. The eastern tree was a splendid willow, that waved about in the sun, and caught all the light that shone into the silver edges of his leaves, till they grew to have a glimmer of their own, and a life, and a dance, when the wind came to blow them over.

Ailish stood under the willow-tree. The little stream ran by in the sound of its own soft voice, which grew louder as the dusk grew deeper; and she listened with love to the voice of the stream, and went down to stand by the water. To-morrow she would not hear the stream run by in the dusk; to-morrow she would feel the stillness in the great Glen of Cloy.

Her little brown kid had wandered away from the place where he was tethered. Ailish followed him, and called, and could not find him. She called again, and heard him bleat, as it seemed, far away. Following the sound, she heard him again, and hastened on; but still the cry came back from a distance, and still it drew her on. At last she stayed, and said—

'I cannot.'

For now she stood at the foot of the Fairies' Mound, the round hill of Tievara. And all the Glen's folk knew that whoever should wander on Tievara after sunset might fall into the power of the fairies. Ailish was brave, but bravery is for men and women; she wanted no dealings with fairy folk. Yet Ailish was pitiful too, and when she heard a sad little cry up the hill side, she feared the brown kid was hurt; so hastening over the

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