A NATURALIST IN THE GREAT LAKES REGION 



FIG. 20. Portion of so-called 

 the falling of a great meteorite. 



crater" of Canon Diablo, probably made by 



FIG. 21. A spiral nebula with centers of condensation, the great central one 

 giving rise to a sun, the others to planets and satellites. Photo by Mount 

 Wilson Observatory. 



