182 NEWTON S PRINCIPIA. 



Thus Newton found a great discrepancy between the 

 results of observation and theory. He accounts for this 

 by remarking that there are two causes whose effects have 

 not been allowed for. First, the diameters of Jupiter will 

 appear in the telescope greater than they really are. The 

 magnitude of the correction to be applied depends on the 

 size of the telescope, and the care that has been taken in 

 its construction. The greater diameter of Jupiter being 

 37&quot;, the lesser, according to the above ratio, will be 

 33&quot; 25&quot; , add thereto 3&quot; for the effects of aberration, 

 and the apparent diameters of the planet will be 40&quot; and 

 36&quot; 25 &quot;, which are to each other in the ratio of 1 1 to 

 10|, very nearly. Secondly, Newton remarks that the 

 theory assumed Jupiter to be of uniform density. But 

 this is not likely to be true. 

 5. 



6t J- NOTE IV. 



8. 



