274 RELATION OF PHYLLOTAXIS TO MECHANICAL LAWS. 



ing circles, may be adapted from a special case of electrical 

 distribution.* 



Such a diagram is then an eccentric homologue of fig. 24, and 

 any phyllotaxis system for uniformly progressive eccentric dis- 

 tribution may be taken from it. It must be noted, however, that 

 although a diagram in terms of circles has been utilised because 

 it is easier to construct, there is no suggestion that the circle 

 represents the true shape of the periclinal curves. This diagram 

 is a special case, and is only taken so far as it goes, in that it will 

 give the correct appearances within the error of estimation by the 

 eye, and is, at the same time, a mathematically correct orthogonal 



* For the construction of this figure I am indebted to Mr E. H. Hayes. 

 It represents one half of two systems of coaxial circles which intersect ortho- 

 gonally, which would represent in electricity the lines of magnetic force around 

 two equal and parallel currents travelling in opposite directions. The data 

 for drawing it are as follows :— 



Let XX' and YY' be rectangular ordinates intersecting at the origin O. 

 From along the axis OX take a point C, 5 inches from O. The centres 

 of the intersecting circles fall along CX and OY, OY' at the following dis- 

 tances. C=the centre of construction, on 00 produced describe circles with 

 centres . . at distance from . . . with radius. 



also the circle through with centre O, and the straight line OC. With 

 these data, intermediate meshes may be filled in empirically within the 

 accuracy of drawing the figure. 



