THE NEBULAR HYPOTHESIS 45 



their satellites were formed, and the sun himself was 

 left as the indivisible residuum. 



In round numbers Uranus is 1,800,000,000 miles 

 distant from the sun. The sun is 866,400 miles in di- 

 ameter. All the planets put together are only equal to 

 1/750 the mass of the sun. 



As the calculation I am about to make does not re- 

 quire close accuracy, let us suppose that if all the 

 planets were to be swallowed up by the sun, his di- 

 ameter w r ould be raised to an even 900,000 miles. Since, 

 then, the volumes of spheres are to each other as the 

 cubes of their diameters, on calculation it will be found 

 that the volume of Uranus' orbital sphere is 64,000, 

 000,000 times that of our augmented sun. If now we 

 imagine the mass of this sun to be evenly distributed 

 throughout the Uranian sphere, our figures mean that 

 one cubic inch of the sun's matter would be diffused in 

 an othenmse absolutely vacuous space as large as the 

 Capitol building at Washington. 



Extending the calculation to Neptune's orbit, which 

 is 2,000,000,000 miles wider, we shall find that our 

 cubic inch of solar substance would have to suffice for 

 a space thrice the size of the Capitol ! 



Here it may be interjected that Laplace's nebula 

 was supposed to be lozenge shaped and not spherical. 

 What right he had to assume so unusual a shape for 

 his cloud, in addition to its accommodating motion and 

 its obliging incandescence, I shall not stop to inquire. 

 Being in a generous mood let me concede at once that 

 this was really the case, and that there was fully as 

 much as a whole tablespoonful of matter for each space 

 the size of the building mentioned. 



Let us now inquire what is the extent of the sun's 

 attraction at the distance of Neptune, in order to as- 



