288 FROM NEBULA TO NEBULA 



upon her axis in rhythmical sympathy with her stricken 

 lord. The inevitable result is that the oceans are caused 

 to shake profoundly in their huge basins, producing not 

 only tidal waves, but also, by the friction on their beds, 

 augmenting the supply of electricity normally furnished 

 by the diurnal tides. The effect of these perturbations 

 on the solid parts of the earth is sometimes, though per- 

 haps not usually, accompanied by earthquakes. The 

 reason for this is not that the perturbations are the vera 

 causa of, but that they precipitate, earthquakes nearly 

 ripe for spontaneous manifestation, much as the slam- 

 ming of a door may cause the glowing coals of a grate fire 

 to collapse when near the point of doing so of themselves. 



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, occurred 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, 



