Mr HOLDITCH, ON ROLLING CURVES. 



, 2& k . (a + by , . ,, 2 



and the equation to a self-rolling curve of n lobes is 



G = /? + A . (« + b)\ . tan- 1 \Tf . V^ 

 \n J be 



'r-b 



a — r 



- ks/(a-r).(r- b) -k.(a + 6).tan-'V- *, 



a — r 



(3), 



where the constants a, b, n, k may be assumed at pleasure, and for any 

 value of /•, the corresponding value of 9 will be obtained, and the 

 curve may then be traced by points. 



The different forms the curves may assume will be best illustrated 

 by an example; thus if a = 10, and 6=1, and k = 114, then if 



- a 148.4 nrfl 



r = 6, = + 2.74, 



w 



154.8 



