2G J. MOEI30N : ADDEESS 



to be on the outer part of the visible universe, and really to 

 form an irregular ring of comparatively dense stars. The Sun 

 is not very far from the centre of this ring, from which it is 

 separated by an enormous interval of space sprinkled with stars 

 mostly at relatively considerable distances from each other. 

 The interval between our Sun and the Milky Way is so great 

 that Newcombe estimates that it takes light no less than 3,200 

 years to cross it, and some astronomers consider the distance 

 very much greater. The Milky Way is composed of an enormous 

 aggregate of clusters of stars relatively close together. It 

 contains stars of all sizes : from first magnitude stars, whose 

 real dimensions, shining as they do across such a stupendous 

 gulf, must be almost absolutely inconceivable, down to a host of 

 minute stars very much smaller than our Sun. It is here that 

 the greatest number of variable and temporary stars occur, and 

 many of the stars and clusters found here are swathed in dim 

 clouds of nebulous matter. It is also here that the very hottest 

 and presumably the youngest stars are fou^nd. The energies at 

 work in the Milky Way must be tremendous, and the cosmical 

 conditions which prevail there must be very different from any 

 which obtain in our part of the universe. A very highly- 

 energised and much less stable state of things seems to exist in 

 that mysterious girdle which encircles, so far as we can see, the 

 whole Scheme of Creation. 



Nebulae are dim patches of cloudy light, as a rule only visible 

 through the telescope. Sometimes they are rounded or annular 

 in shape ; sometimes they present a more or less spiral form ; 

 and sometimes they are of very irregular shape and complex 

 constitution. Sometimes nebulous matter surrounds a star, 

 forming what is called a nebulous star. Sometimes the larger 

 nebiilse contain bright points which are perhaps stars in process 

 of formation. Most of them are of really enormous size, 

 covering a space at least thousands of times as large as the 

 Solar System, while some, such as the great nebula in Orion and 

 the nebula in Andromeda, are immensely larger even than this. 

 As these objects are perfectly transparent, the matter of which 

 they are formed must be of extreme tenuity. They are usually 

 supposed to consist of very tenuous incandescent gaseous matter. 

 Sir Norman Lockyer, on the other hand, thinks that nebulae are 

 vast collections of meteorites moving amongst themselves with 

 extreme rapidity and continually coming into collision with each 

 other and so producing heat and light. The nebulae are all 

 extremely distant objects, and though found all over the 



