VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 317 



revolutions being still quicker, and more regular, and nearer the ball ; and at 

 the 6th revolution of this last hundred, the thread was attracted to the surface 

 of the ball, and, being wet, did not disengage itself, till pulled away ; yet 

 after this, it described the remaining 9«1 revolutions of the hundred, and seemed 

 inclined to describe a great many more, but that he was forced to rest his arm 

 again, which he did for about 8 minutes, then tried again, the thread being 

 fresh wetted, and had 70 revolutions at nearly the same distance from the ball 

 in less than 9 minutes, all very regular, and without any attraction of the 

 thread to the ball. He rested again 16 minutes, wet the thread again, and 

 held it as usual; it was repelled at about -^ inch distance from the ball, but 

 seemed to have no tendency to a circular motion ; yet after continuing stationary 

 about a minute, he perceived a motion about its axis, about which it took 

 several turns; but still had little or no progressive motion, till about a minute 

 longer, when it began to move forward, and continued doing so from west to 

 east, for about 33 revolutions, very regular, but slower than in the last two 

 cases, the string having been held about 10 minutes, and the revolutions per- 

 formed in about 7 or 8 of them. In each of these last 3 times, it whs rather 

 longer before the progressive motion began than usual; and in all the trials 

 of this experiment, he frequently perceived a motion about the axis, which was 

 generally from west to east, though now and then the contrary way. The 

 virtue of the cake n)ust now have lasted near 2 hours ; about 3 quarters of an 

 hour after, he tried again, and had 60 revolutions from west to east, in about 

 10 minutes, the distance from the ball being still less than before, hardly -j- of 

 an inch, scarcely any revolution about the axis appeared, and at the beginning 

 the thread was twice attracted to the ball. About an hour and a half after, 

 the virtue of the ball was not quite gone, the wet thread being repelled, and 

 making 3 or 4 revolutions from west to east, as well as moving a little about 

 its axis the same way. But as it was reasonable to suppose the ball itself in 

 the centre of the cake was now dry, with a feather dipped in water he wetted 

 its surface ; yet found no increase of virtue, rather a diminution of it, the 

 pendulous body seeming scarcely at all repelled; but it is to be observed, that 

 the ball, as it was wetting, twice tumbled over, and rolled on the surface 

 of the cake; by which means the virtue of the cake might be much di- 

 minished. 



It is not improper too to take notice here, that during the revolutions of the 

 wet string, he frequently observed a kind of oscillatory motion, as if there was 

 an alternate intention and remission of the repulsive force. As also that he 

 often took notice of little plucks, and convulsive motions, in the pendu- 

 lous body, and sometimes thought he has felt something like it in his 



