ELECTRIC LIGHTS. 175 



spilling the contents of the saucers if they are very 

 full. 



4. Make one ring to follow another so as to overtake 

 it. If the axes of the two coincide, the forward one will 

 expand, while the oncoming one will contract in diam- 

 eter, permitting the latter to go through the forward 

 and larger one, when each will assume its original 

 dimension. 



5. Project one ring after another so that they may col- 

 lide. Each will be seen to be deformed and each will 

 vibrate, assuming oval shapes with axes at right angles 

 to each other, thus indicating that the rings are elastic. 



6. Project a ring so that it will pass near a suspended 

 fibre of thread or other light body. The thread 

 will appear to be repelled from the front and attracted 

 by the back of the ring. 



7. A ring formed by the oval hole will move forward 

 like the round one, but will vibrate energetically, going 

 through the phases mentioned in experiment 5. 



8. The triangular hole will likewise give a vibrating 

 ring, as will one generated with any other form of 

 orifice, so that it is impossible to have a ring that will 

 maintain any other form than the circalar one with its 

 phases of vibration. 



9. With the double aperture slide, two rings will be 

 formed simultaneously, but instead of producing them 

 as the larger ones were, they can best be made by 

 a tap with the finger upon the cloth back near to its 

 edge. The rings will be small but well formed, and 

 move so slowly that their motions may be easily 

 watched. 



10. Observe that when the two are produced they 

 invariably collide, they never move off parallel with 

 each other. 



