bright Dog-star, Sirius.
DAILY MOTION OF THE EARTH.
The following dialogue took place one evening on deck:—
“Well, my little fellow, what is there which so attracts your attention? for you have scarcely moved for this last half-hour.
I have been looking at the stars, father.
What is so wonderful in them this evening?
There is something wonderful in them which I never noticed before.
What is that?
I will tell you. When I first came upon deck after tea, I saw a bright star rising like as if it came out of the water. While looking at its pretty light, it seemed to get higher and higher up the sky.
Did it run away from the other stars, and get a head of them?
No. But I thought it did at first, until I had watched, and then I found that the stars around about kept at the same distance from my bright star, and appeared to keep company with it while climbing the sky.
And what else did you see?
Afterwards I thought I would watch the beautiful Sirius. This seemed to be moving on, too. Then I looked at others. But they all appeared to be rolling along after one another.
What do you make of all this?
I can make nothing of it.
What puzzles you, my boy?
Several things. I cannot understand where all the stars are rolling to, why they all keep together so cleverly in their motion, or why they are moving at all.
Did you see any stars setting as well as rising?
Yes, father.
Well, as I want you to find out this subject yourself, I shall allow you to stay up later this evening, to give you time to make a few more observations. Now, follow your bright star a little further. Look at that blue one overhead, and trace his journey. Have your eyes upon Sirius, and the band of Orion.
I will, father, and thank you.”
The boy was left at his star-gazing, and intently was his mind fixed upon his work. It was no vacant stare he gave at the heavens. He had an object before him.
The conversation was afterwards renewed by the father:—
“I should think you were sleepy, James.
No, father: the stars kept my eyes open.
How, now, does your star get on?
Look up there. He has got as far as that.
Where is the blue-coloured one?
O, that has gone down to the western edge.
What of my old friend Sirius, and his neighbour Orion?
They have been travelling the same road.
Well, you must stop star-gazing to-night.
But will you not explain the reason of this curious motion, my dear father, before I go down?
No, my lad, you must have another look at the stars to-morrow evening first.”
The little fellow retired slowly and thoughtfully to his berth; and dreamed of stars and ships in mingled confusion. How he longed for the sun to leave off his shining! He never watched that orb so as he did that day! He saw it rise, ascend, descend, and set. When the short twilight was over, the little twinkling bodies came out one by one, as a few western clouds changed from gorgeous red to colours of a darker hue. He first distinguished Sirius, and then the band of Orion. The blue star took some time to come forth; but when it did, there it was right overhead, as it had been early the last evening. The bright star was again on the tip of the distant waves. He stared again. He remembered how he had left them all the night before, and now the stars seemed in their old places again. His kind father came up to him.
“O, father,” cried the boy, “all my stars have gone back into their places again this evening.
Did you see them travel back as you saw them travel forward?
No. But there they are, though I do not know how they got there.
I think I saw you looking pretty often at the sun, to-day. Did you notice anything peculiar about his movements?
Yes. I noticed that he seemed to go the same road as my stars did the evening before.
But you saw him ascend in the east, rise nearly overhead, and then set in the west. You did not observe your stars do that.
No, father; but I have it. It took a long while for the sun to go all that distance; and I fancy that if I had watched my bright star as long, I should have seen that set in the west also.
Certainly you would.
Well, but how did they get back into their places again?
How will the sun manage to get on the east side, to-morrow morning?
Ah! I see. What will explain the movement of the stars will explain the movement of the sun.
I think you will find it so.
There is only one way by which I can account for this—they must all turn round the earth. Is that it, father?
Everybody used to think so.
But what surprises me is this; as the stars are turning round us, none get before or behind the others. They keep the same distance apart.
Do you not know that all the stars are stuck in a huge mass of blue stuff, called the sky, and that when the sky turns all of them must turn with it, and, unless they tumble out, they must keep in their places?
O, father, you are joking.
Well, then, if they are not joined together, why do they move so uniformly?
That I cannot tell.
No two of the stars are of equal distance from us. They are all scattered through space, like a lot of marbles in a scramble.
Then if they had to move round the world, I am sure they never would keep in such order, especially as some would have to go so much faster than others; for they have a much greater distance to go. They cannot turn round the earth in that way. But yet they seem to do so.
Yes. But just look forward. Do you see how the head of the vessel is dipping into the Bay of Biscay?
I do, father.
But do you notice that as the bow of the ship sinks and rises, all the stars to the southward seem to dance up and
