Count de Bournon on the Laumonite. 



91 



Retrogradations upon the acute angles of the terminal faces, answering to the acute solid angles 

 of the primitive crystal. 





Number 

 of the 

 modifi- 

 cations. 





Anjfles formed 

 by the meeting 

 of the new 

 planes with the 

 terminal faces. 



Angles formed 

 by the meeting 

 of the new 

 planes with the 

 edgesofST-'.SO'. 



1 Angles formed 

 j by the meeting 

 ] ofthenewplanes 

 1 with those of the 

 J5th modification. 



Angle* formed 

 by the meeting 

 ofthe new planes 

 with those of the 

 1 6th modification. 



j 



Nature of the re- 

 trogradations. 





5th. 



It 



li 

 i\ 



■- 1 



£S 1 



. . 98», 5' . . 



. 136" 55' . . 



1 





Retrogradation by 

 a single row. 







1 



1 





6th. 



. . 124-, 56' . . 



. . 110», 4'. . 



. . 153% 4' . . . 





Retrogradation by 

 5 rows in breadth, 

 and 3 laminje in 

 height. 











7th. 



. . 134», 22' . . 



. . 100», 38' . . 



. . 143% 2(5'. . 



. . 170% 34'. . 



Retrogradation by 

 2 rows. 





Retrogradation on the obtuse angles of the terminal faces. 





Number 

 of the 

 modifi- 

 cations. 



1 . 



r 



Angles formed 

 by the meeting 

 of the new planes' 

 with the termiual 

 faces. 



Angles formed 

 by the meeting 

 of the new planes 

 with the edges of 

 92°, 30'. 



Angles formed 

 by the meeting 

 ofthe new planes 

 with those of the 

 8th modificati- 

 on. 



Angles formed 

 by the meeting 

 of the new planes 

 with those of the 

 9th modificati- 

 on. 



Nature of the 

 Retrogradations. 





8th. 



m 



."Si 



a. MO 



. . 105», 7' . . 



164* 53' 







Retrogradation by 

 1 row in breadth, 

 and 2 larainse in 

 height. 













9th. 



. . il8»,22'. . 



. . 151»,28'. . 







Retrogradation by 

 a single row. 











II 1 









10th. 



. . 148% 28'. . 



. . 121% 37'. . 



. . 136% 44' . . 



1 



. . 156% 9'. . 



Retrogradation by 

 3 rows. 





M 2 



