82 Mr. W. W. Rouse Ball [March 12, 



[The Yam Theft. — The successive movements which produced the 

 figure shown in the Lecture may be put in the form of the following 

 rules : — First : Hold the left hand open with the palm facing you, 

 the thumb upright and the fingers pointing to the right and slightly 

 upwards. With the right hand, loop the string over the left thumb, 

 crossing the strings if you like, and let one string hang down over 

 the palm and the other over the back of the hand — we may call 

 these the palmar and the dorsal strings. Second : Pass the light 

 index-finger from below under the palmar string, and then between 

 the left thumb and index-finger, and with its front tip hook up a 

 loop of the dorsal string. Pull this loop between the left thumb 

 and index-finger back on to the left palm. Then with the right 

 index-finger give the loop one twist clockwise, and put it over the 



Fig. 4. — The Yam Thief. 



palmar string on to the left index-finger. Pull the two pendant 

 strings so as to tighten the loops on the thumb and index-finger. 

 Third: In the same way pass the right index-finger from below under 

 the pendant palmar string, and then between the left index and 

 middle fingers, and with its front tip hook up another piece of the 

 pendant dorsal string ; pull this loop back on to the left palm, and 

 with the right index-finger give the loop one twist clockwise, and 

 put it over the palmar string on the left mid-finger. Fourth .- In the 

 same way, working between the middle and ring fingers, hook up 

 another loop of the pendant dorsal string, and put it on the left 

 ring-finger. Fifth : In the same way, working between the ring and 

 little fingers, pick up another loop of the pendant dorsal string, and 

 put it on left little-finger. Sixth : Take off the left thumb loop, 

 and hold it between the left thumb and index-finger ; and, for the 

 sake of effect, to show that the loops are still on the fingers, pull the 

 pendant dorsal string. Finally: Pull the pendant palmar string, 

 and the figure will come off the hand.] 



