498 



SCIENTIFIC RECREATIONS. 



reflected light. So we may conclude the sun to be entirely gaseous, but, 

 thanks to the recent researches in spectrum analysis (already explained), by 

 which the light of the sun has been examined by means of the spectroscope, 

 and split up into its component colours, Mr. Lockyer and other scientists 

 have discovered that a number of elements (metals) exist in the sun in a 

 fused, or rather vapourous state, in consequence of the intense heat. Hydrogen 

 exists in the sun, with other gases unknown to us here, and many metals, 

 discovered by their spectra, which are the same under similar circumstances. 



The sun is supposed to be spherical in shape, not like the earth, flattened 

 at the poles, and to be composed of materials similar to what the earth is 

 composed of, and what it would be if it were as hot as the sun is. Thus we 

 can argue by analogy from the spectra of earthly elements, that, as the sun 

 and star light gives us similar spectra, the heavenly bodies are composed 

 of the same elements as our globe. We can thus form our opinion of the 

 sun's constitution. Mr. Neisen says : 



" With the aid, therefore, of the additional information given us by the 

 spectroscope, it is not very difficult to form a true idea of the probable con- 

 dition of the surface of the sun, which is all that we can see. It is the upper- 



Fig. 548. Sun spots. 



lying strata of a very dense atmosphere of very high temperature an 

 atmosphere agitated by storms, whirlwinds, and cyclones of all kinds, 

 traversed by innumerable currents, and now and then broken by violent 

 explosions. Above the brilliant surface which we see is a less dense and 

 somewhat cooler upper stratum, which, though hot enough to shine quite 

 brightly, is quite invisible in the presence of the brighter strata beneath it." 



SUN SPOTS, as they are generally called, are hollows in the sun's 

 vapoury substance, and are of enormous extent ; and there are brilliant places 

 near those spots, which are termed faculce. These spots have been observed 

 to be changing continuously, and passing from east to west across the sun, 

 and then 'to come again at the east to go over the same space again. Now 

 this fact has proved that the sun turns round upon his axis, and although 

 he does not move as we imagine, from east to west, round the earth, the orb 

 does move in fact, the sun has three motions : one on his axis ; secondly, 

 ' a motion about the centre of gravity of the solar system, and a progressive 

 movement towards the planet Hercules. 



If we examine the surface of the sun through a proper telescope, we 



