362 PHYSIOGRAPHY. [CHAP. 



times 107 times as great as the earth's section. And if the 

 vohiiiies, or bulks, of the two bodies were compared, it 

 would be found that the sun's bulk is 107 X 107 X 107 

 times greater than the earth's bulk. In other words, it 

 would require more than a million and a quarter of bodies, 

 having the same bulk as the earth, to be rolled together, in 

 order to form a globe equal in size to the sun. 



No adequate notion of the dimensions and of the distance 

 of the sun is gained by casting the eye over the figures, 

 which represent these magnitudes. But some conception of 

 its enormous size may be formed by reference to Fig. 118, 

 which shows a section of the sun, taken through its centre, 

 compared with a similar section of the earth. It was shown in 

 Chapter XIX. that the earth is a ball of vast dimensions ; 

 but it is, seen by Fig. 118, that this huge ball sinks into 

 utter insignificance when compared with the mighty sphere 

 around which it revolves. 



As to. the distance which- separates the sun fram the earth, 

 that may be represented in a variety of ways ; but, by none 

 perhaps more strikingly than by that which- Sir John 

 Herschel has employed. He tells us that the ball of an 

 Armstrong loo-pounder quits the gun with a speed of about 

 400 yards per second. Now if this velocity could be kept 

 up it would require nearly thirteen years before the ball 

 could reach the sun ! 



Soon after the discovery of the telescope, it was directed 

 to the examination of the solar disc. It was thus found, in 

 the beginning of the seventeenth century, that the sun's 

 face, instead of being uniformly bright, is usually spotted 

 with dark patches. Very little observation is needed to 

 show that these spots are not constant, either in shape, or in 

 position : sometimes indeed, though but rarely, they are 

 altogether absent, and the face of the sun then seems per- 



