PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 683 



been able to present the subject to the friends of science m a sys- 

 tematic form, and in connection with the serial relations of the 

 square roots of the distances. 



Definite Width of the Rings ok Intervals, and the Laws of 

 Their Increase with Distance from the Sun. 



I have said that the rings must have been narrower the nearer 

 they were to the sun. The reason is, that it requires less difference 

 of the distances near the sun to obtain a given difference (1,582) of 

 orbital velocities. This will be seen by inspecting the tables 

 which represent the velocities and distances of the planets. The 

 two known planets that differ most in orbital velocities, are those 

 nearest to the sun and to each other, namely, Venus and Mercury; 

 they differ in their velocities nearly 30,000 miles per hour, yet they 

 differ in distances from the sun only 27 millions of miles. The 

 two known planets that differ least in their velocities, are those 

 most distant from the sun and from each other, namely, Neptune 

 and Uranus; they differ in distance about 1,000 millions of miles, 

 but in orbital velocities they differ only 3,160 miles per hour, 

 which is nine times less than the difference between Venus and 

 Mercury. Since the nearer bodies are to the sun the less differ- 

 ence of distances was required to obtain 1,582 difference in orbital 

 velocities, it necessarily follows that the rings must have been 

 wider the further they got from the sun. 



Formation of Planets from Rings. 

 The nebula must have become divided into rings as soon as the 

 sun was sufficiently large and attractive to establish orbital mo- 

 tions in the surrounding secondary matter. We han^e already 

 seen reason to conclude that the resisting medium caused the 

 nebulous matter to move interiorly by spiral paths toward the 

 sun. This proceeding did not stop when the rings were formed; 

 on the contrary, it was probably the means of forming rings into 

 planets. A large mass of the lighter portions of nebulous matter, 

 situated in the outer part of a ring, would be certain to move spi- 

 rally to the inner edge; in doing this it would, of course, attract 

 to itself nearly all the matter of the ring, and thus form a globular 

 planet. Two masses, moving in the same or1)it, at a great distance 

 from each other, would never come together. But let one of the 

 masses be composed of much lighter materials than the other, and 

 the resisting medium would have a greater effect upon it, and 



