CALIFORNIA ACADEMY OF SCIENCES. 3GT 



I find that the needle may be interpreted as a combination of 



the cube with three pentagonal dodecahedrons, one of which, c, 



is new, viz: 



a = oo co (100) 



oo O 2 

 b = — ^— * (210) 



co O 1 



c = — —^ n (470) 



co o 4 



d = - — g-* tt (780) 



The following table of observed angles taken from the above 

 readings, and compared with the calculated, will make this 

 evident: 



OBSERVED. CALCULATED. 



a 1 :b l 146° 20' 146" 19' 



b x :cP 165 164 52 



c l :c 3 120 29 120 30 



c 2 :a l 119 50 119 45 



d 1 :a l 131 20 131 11 



d l : c l 168 24 168 34 



These needles furnish thus a very striking illustration of the 

 extreme elongation of a tesseral crystal parallel to one of its 

 chief axes, and of a failure of faces to develop; for of the sixteen 

 faces that should have appeared in the lateral zone of the needle, 

 but six are to be found. The ends of the crystal are both broken 

 so that the original terminal development could not be studied. 



Fig. 10 is a greatly enlarged drawing of the needle and Fig. 

 10 b , drawn in parallel position to Fig. 10, is the complete crystal 

 with all of its faces as it would have developed under favoring 

 conditions. 



This needle was broken from a specimen coming from the 

 upper level mentioned by Superintendent Buckminster. Another 

 needle, from the lower level, was examined and found to contain 



three of the lateral faces of the cube, and the four lateral faces of 



co O | 



the new dodecahedron c = — — 3 — -(470). No traces of the 



other forms mentioned above are present. 



