Ill 



WEIGHING THE WORLDS 



TO speak of the weight of the world is to take 

 obvious liberties with the meaning of words. 

 Weight is the familiar term by which we indicate 

 the attraction exerted by the earth on any given 

 portion of matter at its surface. Since the earth as 

 a whole obviously can not attract itself, it is in a 

 sense a misnomer to speak of it as having weight. 

 A more exact usage of words makes it necessary to 

 speak of the earth's mass rather than its weight. 

 But inasmuch as the only method of determining 

 the mass of any substance with which the average 

 reader is familiar is to determine its weight, the two 

 words have come to seem equivalents in common 

 parlance, and to speak of weighing the world con- 

 veys an altogether precise and accurate idea of the 

 feat accomplished in what is more technically, de- 

 cribed as determining the earth's mass. 



There are several methods by which this para- 

 doxical feat of weighing the earth may be accom- 

 plished. The one which was first put to the test 

 depends upon the principle of determining the attrac- 

 tive influence of the mass of a mountain as balanced 

 against the attraction of the earth as a whole, which 

 latter attraction, it should be explained, is exerted 



