366 POPULAR SCIENCE MONTHLY. 



wliicli is the center of the attraction we call gravity ; the much 

 greater " lightness " of the materials composing the planet; and 

 the great centrifugal or " throwing-off " force at the equator, due 

 to the rapid rotation, and which would, of course, counteract to 

 some extent the downward pull of gravity results in making 

 but a slight increase, so that a man weighing one hundred and 

 fifty pounds on the earth would weigh only about six pounds 

 more at Saturn's equator. At the poles, however, the change is 

 more marked, since there is no centrifugal force, and the polar 

 flattening, due to the rapid rotation and consequent bulging at 

 the equator, brings one nearer the center of the planet. In this 

 case the increase would be about thirty- six pounds, and would 

 probably be found somewhat uncomfortable to us. 



However, it is by no means certain that the dimensions seen 

 through the telescope are the right ones to consider in this man- 

 ner. If all we have ever seen of the planet is the outer side of its 

 cloud envelope, it may be that the true surface, provided there is 

 one at all, is far beneath the tops of these rolling cloud masses ; 

 and if there is no real surface yet if the terrible struggle of 

 fire and water for the mastery is still in full sway no one 

 can tell just what the size of the globe may be when the crust 

 finally forms and the real planetary life begins. This " dis- 

 tended mass of liquid fire " may have shrunk i^erceptibly by that 

 time. 



This also brings up one other interesting query. The spectro- 

 scope has proved that the sun and stars are composed of materials 

 with which we are familiar in our laboratories, and Saturn as 

 well as the other planets must be composed of the same chemical 

 elements, though probably with wide variations in combination 

 and distribution. If, then, Saturn were to approach the earth in 

 the density of its composition when it reaches a corresponding 

 stage in its planetary growth, it must shrink to one eighth its 

 present volume, or one half its present diameter. On the other 

 hand, if its size remains anywhere near the present dimensions, 

 we shall almost be forced to the conclusion that this great globe 

 may eventually become one vast ocean a dreary expanse of 

 water with perhaps only a relatively small solid center, thou- 

 sands of miles below the surface. 



But whatever its future, it will always remain a most interest- 

 ing object of study, and no one can consider it thoroughly with- 

 out being inclined to agree with Richard Proctor, that here cer- 

 tainly must be a world " altogether more important in the scheme 

 of creation than the globe on which we live." 



