I am not sure of that, father; for ever since you proved that the Fixed stars were not fixed, I think I might some day find a bright friend gone on a visit to another universe somewhere; perhaps, getting into such agreeable society as to have no wish to come back again to our visible universe; or, maybe, to pop back again in his place. It so happens, James, that what you have imagined, really takes place. Some stars do really disappear, to return, or not; and others, wholly strangers to us, come within observation. That is the queerest thing you have told me yet. What droll fellows the stars are, after all! How they do wriggle about, polkaing here, doubling there, and fielding about like boys at cricket. I shall never be surprised at any funny trick you ascribe to them. To begin with the _Variable stars_, of which there are known about one hundred. There is Mira, which is invisible five months in the year. It goes and comes again. Where could it have got to? Some think it revolving round a dark object; and, of course, becoming invisible when on the other side from us. One passes through three magnitudes in one month. But I must give you the history of such a curious star in the Whale. For two weeks you might see it a noble star of the second magnitude. It gradually dims, till it goes fairly out of sight in three months. For five weeks you see nothing of it. It then reappears. Altogether it seems to have a revolution of 322 days; and is, therefore, one of the _Periodical_ stars. I should call it a variable periodical. There is another in Cepheus, which grows to its full light in thirty-eight hours only. There is one in the Lyre taking ninety-one hours. Some fancy that the dark appearance may be owing to huge spots on the suns coming into view as the suns turn round. But there is still another sort of star--the _Temporary_. Do they come and have a look at us in their birth, and then disappear never to return? I will tell you the history of one. In 1572 an astronomer saw it shining in the daytime. He could not find it in his star catalogue at home. Day after day it grew brighter and brighter, till it blazed far more than either Sirius or Jupiter, and could be plainly seen in the noontide sun. It then grew dim gradually, and in two years went away altogether, without returning since. That is temporary, and no mistake. But still I guess they will find him turning up some day and becoming a regular Periodical. There is a wonderful star, Argus, in Argo. Two hundred years ago it was of the fourth magnitude only. In 1834, Sir John Herschel, when at the Cape of Good Hope, found it a second magnitude. The light was three times stronger at the end of 1837. Next month it was brighter than any star here but Sirius. It faded awhile, and then increased, till, in 1844, it was equal to Sirius itself.