CHAPTEE VIII. 



A NEW METHOD OF WORK. 



1. Details of 'the Solar Surface. 



WE must now pass to details of another order. Those we 

 have given refer to the light of the sun taken as a whole. 

 But it is in the highest degree necessary for the purposes of our 

 present inquiry, that we should not content ourselves with this 

 general view since when we pass from Kirchhoff' s work we 

 pass to work done on minute portions of the solar surface. 

 This we must now consider, and it is desirable that I should 

 preface it as briefly as may be by a reference to the various 

 differences observed in different parts of the sun. 



When we look at the sun with a powerful telescope, taking 

 all needful precautions (never look at the sun with a small 

 telescope, for this is a most dangerous proceeding), we find it to 

 be by no means the immaculate body it was thought to be by 

 the schoolmen. Here and there on the disc, but generally 

 limited to those parts of it a little above and below the equator, 

 dark spots may be observed. These generally exhibit three 

 shades of darkness, and float, as it were, on the general bright 

 surface of the sun called the photosphere, the darkness of the 

 spot increasing towards the apparent centre. We have first 

 the penumbra, then the umbra, then the nucleus. But some- 

 times the darker portions are excentric, and very irregular in 

 outline. 



