Miscellanies. 208 
lustre. ‘The angles quoted were obtained by Prof. Shepard and 
Mr. Dana; those of observation by the former gentleman from the 
crystal represented in fig. 2, and those of calculation by the latter. 
The faces of this crystal, though quite bright, were somewhat curved, 
and consequently there was considerable variation in the angles ob- 
tained with the reflective goniometer. 
Fig. 1. Fig. 2. 
Angles by the Reflective Goniometer. Angles from calculation.* 
‘Pie= 102° 45/ 103° 42’ 
PM 100 99 45 
8, € 121 46 
Pia 140 10 138 38 
Mie 133 30 133 30 
Mie 138 1388 29 
M ¢ eé 161 17 
ee 106 50 107 6 
eta 142 30 | 143 33 
esé 118 117 47 
eta 141 50 
ee 92 20 90 
éia 100 15 
eta 131 22 
Ze 126 25 126 27 
a:a(over summit) 92 30 93 30 
The description of Fig. 2, after the notation of Naumann, is as 
follows : | 
aPo.aP.aP’o.0P’2.Po.P/m.—P.—Po. 
Gu Vi ce e a é a 
* The observed angles assumed as data for the calculation of the interfacial 
angles of the crystal are as follow: M:€=136°30/; €:4 =140° 10'; €: 4 =126°25/, 
The axes, a:b: c¢='9277:1:1024. 7 =76° 18’. 
