The boy was found by his father looking at the placid face of the heavens.
“What, boy! at your old post, staring at Orion again.
I’ll tell you what I was thinking of, father. You see the world is like this ship—always on the rock, never really still—and I was thinking how pleasant rest is, and what a lot of it they must get up there in the fixed stars.
Not so; we are now learning that they are, like some boys, not so steady as they look.
You surely don’t mean to say that such respectable old folks as Sirius and his bright friends ever go dancing about in the heavens like giddy Venus and Mercury? I know they appear to tumble about over our masts in a storm at night, but that is because the ship is rolled over by the winds and waves.
It is really true that they do not keep to their places, though the change of position is so very slight as not easily to be discovered. Your friend Sirius, for instance, has been closely watched, Dog as he is, for two thousand years. We know what his place was that time ago, and what it is now; and it has shifted to the southward half-a-degree.
That is as much as the apparent diameter of the sun. But has he any company in his rambles?
Yes; the Bull’s Eye, Aldebaran, has kept up pace with him.
Quite right to have an Eye upon the Dog. But has any exact difference of position been observed since we have had good telescopes?
The star sixty-nine of the Swan has been well watched for fifty years, and found to have gone on four minutes—the eighth part of the moon’s face. A star in the Indian has moved seven seconds in the year. They are not fixed, like the ancients thought they were, in a crystalline sphere; or riveted, as Aristotle taught.