660 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



acting inward, perhaps first balling together some small liquid or' 

 solid masses, like the meteorites, and series of these meteorites 

 revolving as rings, and attracting one another, diminished in 

 quantity but increased in size. The largest having always the 

 advantage, as for the very reason of their greater size, the extent 

 of attractive power went further, and growing larger by acces- 

 sions from all directions, they continually became more and more 

 heated, by the triple cause of converging motion, pressure on 

 their centres, and mutual chemical action by the contact of the 

 different elements constituting them. 



The final effect of the sideward motion originated on the outside 

 of an irregular shaped gaseous mass, is easily illustrated if we 

 imagine an inclined plane running around the w^hole earth, and 

 which at its lower end would of course be several thousand feet 

 below its beginning; a body rolling down this plane, and thus 

 moving around the whole earth, having reached the lower end, 

 would after the well known laws of gravitation have obtained a 

 velocity equal to that it would have obtained by truly falling 

 through the same few thousand feet perpendicularly downward, 

 of course taking account in both cases of the resistance of air and 

 friction. In the same way we obtain nearly the velocity of any of 

 the planets in its orbit, when we add to the velocity of the next 

 outer planet, the velocity a body would obtain, when falling 

 through the distance between this outer planet and the inner one. 

 This is the key to Kepler's third law, which he however only ob- 

 tained in an empirical way. 



[Here the Dr. explained this law, and by comparing the velo- 

 city of the different planets, showed that the facts verified the 

 above theory.] 



Durino- the condensation of the nebular mass out of which our 

 present planetary system has been formed, every atom moved in 

 a spiral toAvard the centre, thus not only the angular velocity was 

 increased, but also the direct velocity, after the same law as is the 

 case with any falling body; finally the velocity became large 

 enough to balance gravitation, and a ring of more or less stability 

 was formed, which by breaking up gave birth to each planet. 



When motion is origin'hted from the centre of a mass and is com- 

 municated outward, the inside of each fluid ring formed, will move 

 more rapidly than its outside, and wdieu the ring breaks, the direc- 

 tion of rotation of the resulting globes, will be opposite to that of 

 the central cause. 



