152 THE MEANING OF EVOLUTION 



who were willing to consider the question as open to 

 human solution. This theory is known as La Place's 

 Nebular Hypothesis. When men began to study the 

 heavenly bodies with the newly invented telescope, 

 new ideas naturally sprang up. Among the objects 

 which the glass disclosed were the nebulae, which are 

 great clouds of fire mist, glowing masses of gas. They 

 are scarcely visible to the naked eye, but are among 

 the most interesting objects in the heavens when seen 

 through a telescope. The other suggestive heavenly 

 body was our sister planet, Saturn. Besides having 

 a full complement of moons, Saturn has around it, as 

 distant as we would expect moons to be, three great 

 rings. These look very much as if one's hat, with 

 an enormously wide brim, should have the connection 

 between the rim and the hat broken out completely, 

 but the rim should still float around the hat without 

 touching it and should steadily revolve as it stood 

 there. The rings of Saturn are not solid like the sug- 

 gested hat rim. They are evidently made up of a 

 great number of very small particles, each moving 

 around the center of Saturn. But the great cloud of 

 them is spread out flat. At the distance which Saturn 

 is from the earth they look as if they made a solid 

 sheet. Furthermore, they do not form, as it were, 

 one continuous hat rim, but it is as if the rim were 

 broken into three circular sections, each bigger than 



