Smithsonian Report, 1931. — Jeans 



PLATE 2 



1. The Great Nebula in Andromeda (Messier 31) Taken at Yerkes Ob- 

 servatory OF THE University of Chicago 



This, the most conspicuous of all spiral nebulae, lies far outside our Galactic System. It takes light 

 about 800,000 years to reach us from it and 40,000 years to cross it from one side to the other. 



2. The Famous "Whirlpool" Nebula (Messier 51 in Canes Venatici) 

 This, the first nebula in which the spiral structure was discovered, is about 1,000,000 light-years distant. 



