152 Mil. E. Hunt on certain Phenomena connected icitli 



own theory, according to which the top keeps up, and even rises to a 

 vertical position in consequence of the frictional action of the rotating 

 peg point on the table or floor. I can aiTange my apparatus so as to 

 act like a common peg top ; and, in partial confirmation of Mr. ElUot, 

 it shows the phenomenon without the peg point rotating at all. 



In giving his own explanation, Mr. Elliot uses the diagrams which I 

 copy in figs. 12 and 13, with some additions. The line c p, fig. 12, is 

 the axis of the peg top ; the ellipse a e is a perspective view of a ring, 

 in which the mass of the top is supposed to be concentrated. The top 

 being inclined, gravity tends to make it fall over and turn in a vertical 

 plane round the point p. Mr. ElUot says, that every point in the lower 

 half of the ring tends to fall, and every point in the other half to rise. 

 This is incorrect, for all the points to the right of the vertical o p, tend 

 to fall, and only the few points on the other side of that Une to rise — 

 whilst, if the top were a little more inchued, every point in it would 

 tend to fall. What need is there to depart from the simple statement, 

 applicable to any inclination of the top, — that every point in it tends 

 to turn in the same direction round the point p ? Mr. Elliot continues : 

 — " But the point b, in beginning to fall, is, at the same time, carried 

 forward from B to b, conveying the tendency to fall with it, so that the 

 actual fall would take place at a point h, immediately in advance of the 

 lowest ; at the same time, the highest point a, beginning to rise, carries 

 that rise forward to a point a, immediately in advance of the highest. 

 Now, let us observe," he adds, " the effect which this has produced upon 

 the top : the point a in advance of the highest is raised, and the point 

 h in advance of the lowest is depressed ; this change tilts the top over, 

 if I may so express it, aside from its former inclination." 



With all deference I must submit that this supposed tilting over 

 in a direction at right angles to that in which gravity is soUciting the 

 top, by no means follows from Mr. Elliot's premises. Observe, he does 

 not say the particle at b does not fall, but that the actual fall takes 

 place at a point 6, in advance ; that is, the fall must be measured from 

 the position the particle would then have had by the rotation alone. 

 The same effect would be produced as regards the point B if it were 

 first turned about the axis c p, supposed fixed, and then moved through 

 an angle round the point p, equal to, and in the direction of, the fall. 

 Likewise, in the case of the opposite point A, the effect described rather 

 vaguely by Mr. Elliot, would be obtained by turning that point about 

 the axis c p, supposed fixed, and then moving it round the point P in 

 the direction of the fall. Mr. Elliot gives no reason why the very same 

 description should not apply to every other point of the top ; and if it 

 is correct, their positions, after a short interval of time, will all be an 



