550 SCIENTIFIC RECREATIONS. 



and a green day, for instance, alternating with a white one and with darkness, 

 might arise from the presence or absence of one or other or both above the 

 horizon." 



LOST AND NEW STARS. 



We may have perhaps read the "Lost Pleiad," and wondered what has 

 become of the star supposed to have dropped out of the cluster so well 

 known in the constellation Taurus the Pleiades. There are seven stars, of 

 which six are visible to the average eye, and the ancients used to declare 

 that one of the seven sisters (the daughters of Atlas and Pleione) hid herself 

 because she had married a mortal, while all her sisters wedded gods. It is 

 not improbable that one of the seven, formerly distinguishable with the 

 unassisted eye, may have disappeared or been lost; but it is certain that 

 strong eyesight can see more than seven now, and in the telescope there are 

 about one hundred. 



And it is a fact that some stars whose places have been carefully 

 marked in the catalogue have subsequently disappeared. Many errors may 

 have been made, and stars put down where no star existed, so a succeeding 

 observer has not been able to find the star indicated. But, on the other hand, 

 we may admit that stars have been lost to sight, and to compensate us for 

 any such disappearances new stars are frequently observed, and these are 

 very remarkable phenomena. About 121 B.C. Hipparchus perceived a new 

 star, which was visible even in the daytime, and on subsequent occasions 

 others came into existence viz., in the years 945, 1264, and 1572. In the 

 last-mentioned year Tycho Brahe suddenly perceived the new star, which 

 was at first very brilliant. It grew fainter and fainter, after first gaining in 

 .intensity, and disappeared entirely in 1574; and at other times stars have 

 been seen which remained only for a short time, and then disappeared. 



The star discovered by Tycho Brahe was seen by him when walking 



across the fields one night, and he encountered 

 peasants who were gazing at the new luminary. 

 It was so bright that it threw a shadow from 

 Brahe's stick. The new arrival appeared in 

 " Cassiopeia," under the lady's chair, forming, 

 as pictured in the diagram, an irregular square. 

 The strange star is the largest. 



Some stars exhibit extraordinary fluctu- 

 ations, and one discovered by Mr. Birmingham 

 Fig. 622.-Cassiopeia. in 1 866, decreased rapidly and sank away to 



about the tenth magnitude, and then got brighter, and again diminished in 

 splendour. The "Eta" Argus has also been subjected to many fluctuations 

 likewise, and such alterations have gained for these luminaries the name of 

 " Variable Stars." 



In the accompanying little chart there will be perceived two particular 

 stars, named Algol, "the demon," and Mira "the wonderful." The latter is 



