There have been a great many theories about comets, but there is only one of them in which I have placed any belief.

You know that as a comet passes around the sun, its tail is always pointed away from the sun, so that no matter how rapidly the head shall be moving in its orbit, the end of the tail--in order to keep its position--must move with a rapidity impossible to conceive.

If this tail were composed of nebulous mist, or anything of that sort, it could not keep its position.

There is only one theory which could account for this position, and that is that the head of a comet is a lens and the tail is light.

The light of the sun passes through the lens and streams out into space, forming the tail, which does not follow the comet in the inconceivable manner generally supposed, but is constantly renewed, always, of course; stretching away from the sun!" "Oh, dear!" ejaculated Margaret.