E. S. Dana—Stibrate from Tapan. 221 
(248) 48° 1’, for o, (253) 54° 17’, for o, (268) 59° 7’, for a, (278 
62° 55’, for o, (288) 65° 10’. The corresponding calculate 
sages are respectively ¢, 10° 343’, o, 29° 153’, 6, 40° 24’ 
d 
viz: for 4, (818) 77°, required 76° 403’; for a, (328) 64° 30’, 
(6 59 The 
ments given in the table above; in the same horizontal zone 
(503 to 010) with it, three other planes were observed, viz: 
8 
° 59, required ; 
In the zone with a (100) and a, (5:10°3), two planes were de- 
termined, viz: V (10-30-9) measured angle on @,=8°, required 
‘ Set W (20309) measured angle on w,=7°, required 
the zone g (130) and 7 (3538), the measured angle on 6 (010) was 
27 27° 57’ 
d 18° 2’, | 
On w, (5°10°3) was 28° 294’, calculated 23° 29’. Of the remain- 
Ing planes X (481) was in the zone [(110) to z (101) and the 
measured angle on / was 14°, required 13° 42’. The plane I 
(846) was in the zone W (028), ¢ (146) ¢, (228), the angle meas- 
ured on NV was 28° 20’, required 22° 584’. The plane ¥ (829) 
was in the zone a, (629) and a (100), the following angles were 
also measured Fao 208)=12° 30’, required 12° 23’; ¥ 218 
10°, required 9° 56’. The plane 7'(62)) was determined by the 
following measurements: 7's 7’ (521 .521)=42° 15’, required 42 
34’; Trh (810) 11°, required 10° 48’; 7’, [=81° 45’, required 
82° 16". The planes & (144) and H (2655) were in the zone 
with wu (011) and a@ (100), the angles measured on u were 10° 
and 15° 30’ required 10° 11’ and 16° 2’. : 
above pages were written the writer has received 
from Mr. Stadtmiiller, to whom he is otherwise much indebted, 
Some additional material which promises to afford some new 
Points; the study of this is necessarily deferred. 
August 3,1883. 
