118 DESCENT OF A HEAVY BODY IX A RESISTING MEDIUM. 



|>ositive direction will be equal and opposite to the negative effect due to the 

 angular velocity during a whole revolution. 



The motion will then consist of a succession of equal and similar parts 

 j>erformed in the same manner, each part corresponding to half a revolution of 

 the paper. 



These considerations will serve to explain the lateral motion of the paper, 

 and the maintenance of the rotatory motion. 



Similar reasoning will shew that whatever be the initial motion of the 

 |>aper, it cannot remain uniform. 



Any accidental oscillations will increase till their amplitude exceeds half a 

 revolution. The motion will then become one of rotation, and will continually 

 approximate to that which we have just considered. 



It may be also shewn that this motion will be unstable unless it take 

 place about the longer axis of the rectangle. 



If this axis is inclined to the horizon, or if one end of the slip of paper 

 be different from the other, the path will not be straight, but in the form of 

 a helix. There will be no other essential difference between this case and that 

 of the symmetrical arrangement. 



Trinity College, April 5, 1853. 



