VARIA1U.K AND LOST STARS 131 



of the common people, where a practised 



tore there was no star vimble an hour or two before. 



wan he to conclude that it had flared up an if it were 



, -in i th<u it would go out aa the fire died down ? 



i he aaw a star brightening, paling, going out, and 



brightening again every three or four days, or weeks 



or months, or every three years, was he to 



irk bodies of vast size were thrusting 



themselves between that distant sun and our eyes, 



eclipsing it, in fact; or that immense reaches of un- 



Hghted space, or dark regions on its surface, were 



turned for a time towards us, as it revolved on its 



Dark spots on a sunny stars surface and a 



rotation more or less rapid were the causes accepted 



i erschel from previous astronomers for this change 



:i.-s in what are called changing or variable 



ltel lie examined seven that were th< n known. 



riods were 3, 5, 6, 7, 331, 394, and 497 days. 1 



It, however lews were discredited by 



the sudden bound from 7 days to 331 I "nloss a star 

 were found bridging the gulf between these two, he 

 would not have had confidence to give his theory to 

 1. But the star a Herculis seemed to him 

 to bridge the gap, and satisfy the theory. Its period 

 was found to be about 60 days. These and other 

 changes on the face of the heavens, known for many 

 years and registered in books, formed Herechel s pre- 

 lude to the work he had set his heart on, The Con- 

 struction of ike Heavens, That they are a building, 

 a wonderful temple consecrated to Almighty Power 

 and Wisdom, he never doubted. To discover the plan 



Tnnu. (1796), pp. 456-56. ProftMor Hokien girct the 

 aoabm M 8, 5, 6, 7, 534, 404, and 44 (p. 193). 



