THE SUN. 51 



That belongs to mechanics, and we must take it for 

 granted. But in order to understand how it is possible 

 to pass from this familiar case that we see every day 

 before our eyes, to that of a vast globe like the earth 

 revolving in an orbit about the sun, it will be neces- 

 sary to enlarge the scale of our ideas of magnitude. 

 We must try to conceive a similar degree of command 

 and control exercised over such a mass as our globe, 

 and over the much greater masses of the remote planets, 

 by the sun as a central body; hardly moved from its 

 place, while as it were swinging all the others round 

 it. And for this purpose it is necessary to possess 

 some distinct conception of what sort of a body the 

 sun really is of its size of its distance from us of 

 its weight or mass and of the proportion it bears to 

 the other bodies, the earth included, which circulate 

 round it. 



(5.) It is strange what crude ideas people in general 

 have about the size of very distant objects. I was read- 

 ing only the other day a letter to the Times giving an ac- 

 count of a magnificent meteor. The writer described it as 

 round, about the size of a cricket-ball, and apparently about 

 100 yards off. Many persons spoke of the tail of the 

 great comet of 1858 as being several yards long, without 

 at all seeming aware of the absurdity of such a way of 

 talking. The sun or the moon may be covered by a three- 

 penny piece held at arm's length : but it takes a house, 

 or a church, or a great tree to cover it on a near horizon, 

 and a hill or a mountain on a distant one ; so that it 

 must be at least as large as any of these objects. Among 



