Page:A Voyage in Space (1913).djvu/289

Rh In the fourth line Tennyson uses both the effects of distance which we have been considering: it reduces the apparent size of objects so that big sea waves look like mere "wrinkles" and it reduces the apparent movement until the rolling of the billows looks like mere "crawling." So the huge globes of the stars dwindle at their vast distances into mere specks of light; and their terribly rapid movements—perhaps a hundred miles a second—look like mere "crawling," so slow that it wanted the eagle-eye of a Halley to detect them.

Astronomers have followed up the clue thus found; by watching the stars very carefully for a century and more they have measured the rates at which a good many of them are "crawling." Some seem to go very slowly indeed; others more quickly; and Sir David Gill has found that those which seem to move quickly are, generally speaking, near to us. Here is a table of his results—