Page:A Voyage in Space (1913).djvu/99

Rh Sir William Ramsay—helium, and neon, and xenon, and a heap of others; so that unfortunate school-boys, instead of having to learn only four things as making up air, as we did, have now to learn a large number of names. Life has a terrible way of getting more and more difficult!

Well, now, one of the reasons why these gases were not found before is that down here in the lowest layers they are very scarce, like rare butterflies, such as the Camberwell Beauty, which is very hard indeed to find in England. But if you go abroad, you may find Camberwell Beauties by no means uncommon. So also, if we could go "abroad" into the upper air, we might find these rare gases much more easily. And there is one thing about them that will interest you, I hope, though their names may be tiresome to learn; they give very pretty colours when we electrify them. We have a series of tubes here filled with specimens of various gases, and when we pass a current through them you will see their different beautiful colours.

There is one other way in which we learn about the upper air, and that is through those meteors, which you saw on one of the balloon slides. A meteor, or, as it is often called, a shooting star, is a bright light like a star that darts across the sky; but it has nothing to do with stars; it is only a piece of stone or metal. Here are some meteors and fragments of meteors; many of the shooting stars you see would be much less than any of these; tiny specks so small that they get burnt up entirely. What makes them shine and burn is the friction of the air as they rush into it. You have heard of producing fire by rubbing two pieces of wood together?