Configurations formed by Floating Magnets. 99 



board I drew a black disk. The centres of these disks I joined 

 by lines, in order to bring before the eye the contours of the 

 configurations. After the diagrams of the configurations had 

 been obtained in this way, they were placed at a fixed distance 

 from the camera ; and photo-engravings were thus made, of 

 about one half the sizes of the original prints. 



The Morphological Laics of the Configurations. — The confi- 

 gurations made by the floating magnets form well-marked 

 groups or classes, which may be designated in order as pri- 

 mary, secondary, tertiary, quaternary, &c. The stable confi- 

 gurations of one class form the nuclei to the succeeding 



ones 



Looking at the diagrams, the reader will see that figures 2 

 to 8 a inclusive form the primaries. Figure 8 b begins the 

 secondaries, for it is the hexagon with 2 for nucleus. Confi- 

 gurations Sb, 8c, 9, 106, 10a, 11, 12, 13, 14, 15, 16, 17, 18a, 

 18 b, and 19 a are secondaries, having respectively for nuclei 

 the primaries 2, 2, 2, 2, 3, 3, 4, 4, 5a, 6a, 7, 7, 7, 8a, 8a. 

 The configuration 10b is not found in the diagrams; it is the 

 same as the 10 which forms the nucleus of 20, only the two 

 central lateral needles are further removed outward from the 

 vertical axis of the figure 10. 



The group of 19 b begins the tertiaries. Of these I do not 

 give diagrams, but indicate their structure by giving the num- 

 bers of the secondaries forming their nuclei, and then give the 

 numbers of needles grouped around these nuclei. Thus, the 

 structure of the configuration formed of 47 needles is indicated 

 by 47 = (18 + 14) + 15 ; which means that 47 needles form a 

 configuration which has 18 for its inner nucleus, surrounded by 

 14 needles, and these in turn surrounded by 15 ; and as 18 + 14 

 forms the tertiary which is the nucleus to this quaternary 47, 

 we enclose 18 and 14 in parenthesis. 



I here give the configurations to 51 inclusive, which form 

 begins the quinaries. 



The configurations of the same number of magnets are let- 

 tered a, b, c, to indicate their degrees of stability, a being 

 always the most stable form. I have, however, lettered the 

 configuration of 8 magnets in the order of their increasing 

 areas, in order to make them serve better for the purpose of 

 illustrating the phenomena of isomerism. Really 8 c is more 

 stable than 8b. 



