THE SUN 251 



Knowing as we do by ocular evidence of the habitual 

 periodical occurrence on the sun of these eruptions, big 

 and little, the question suggests itself whether the sun 

 may not be subject, at longer intervals than we possess 

 records of, to vastly greater convulsions. A phenomenon 

 that seems to lend color to this inference is that of "new 

 stars ". "These", says Doctor W. W. Campbell, "ap- 

 pear with great suddenness at points where previously 

 no star of catalogue brightness (that is, as bright as the 

 ninth magnitude) was known to exist, and occasionally, 

 according to photographic observations, where no star as 

 bright as the twelfth magnitude was recorded. They 

 reach maximum brilliancy in a few days or a few weeks, 

 pulsate through a considerable range of brightness for a 

 few additional weeks, and thereafter decline more or less 

 continously until they become comparatively faint stars. 

 In some cases they assume approximate constancy as 

 faint stars, and in others they seem to go beyond the 

 reach of telescopic power, and later become visible again 

 as faint objects ". What is thus clearly true of some 

 stars may reasonably be true of others, and of our sun ; 

 not simply once, but repeatedly. 



Just such cataclysms as these have, as a matter of 

 fact, occured again and again to our luminary in the long 

 geological past ; not all of them, of course, equally severe, 

 yet comparably so. Violent though they are, however, 

 they are far from being total, nor should it be inferred 

 that they occur at regular intervals any more than do the 

 sun-spots. It is to these solar backslidings that I at- 

 tribute the alternation of genial- and ice ages, for which 

 scientists have so long been groping for explanation in 

 vain; and to them do I also attribute, in chief measure, 

 the enormous alterations of continental levels ushered 

 in with the glacial epochs. Obviously, the sudden libera- 

 tion of a great store of high-temperature gases would 

 greatly reduce the sun's radiation for a long time to fol- 

 low, and centuries would probably pass before he re- 

 cuperated to normal, and still other centuries ere he 

 could succeed in dissolving away the glaciers accumulated 

 during his prolonged lapse. As for the changes of level, 



