176 THE ART OF PROJECTING. 



11. After a collision of two such formed rings they 

 may separate, but when they do they always move away 

 from each other in a plane at right angles to the plane 

 of collision. If the two holes of the slide are horizontal, 

 the rings will bound from each other in a vertical plane. 

 If the holes be vertical, they will bound away from each 

 other horizontally. 



12. If the rings do not rebound, they will each break 

 at the point of contact and weld together into a single 

 ring having twice the diameter, and move on in a right 

 line from the front of the box, but vibrating like the ring 

 formed by the oval orifice. 



13. By using the slide with three holes the rings 

 may rebound from each other after collision for 

 they will always collide as do those formed from the two 

 holes or they may all combine to form a single 

 ring, each breaking apart at the point of contact with the 

 others. 



14. Observe that a ring always moves plane on 

 that is, never sideways or in other directions than at 

 right angles to a plane through itself. (Of course a 

 ring may be drifted about by currents of air, but such is 

 not the proper motion of the ring.) 



15. When a ring strikes upon a surface parallel with 

 its own plane, its diameter increases indefinitely, while 

 the cross section of the ring gets thinner and thinner. 



1 6. Rings having sections of greater density than 

 other parts often show vibratory motions of such parts. 

 Two such on opposite sides of a ring will approach 

 each other and combine midway, heaping up at that 

 place, then each part retreats from the other to meet 

 upon the opposite side of the. ring. A kind of peripheral 

 vibration. If the motions be not very energetic, the 

 denser parts may not separate more than 180 degrees. 



