Editorial Note. 107 
Prof. Hinrichs refers for the angles of species geomet and 
almost exclusively, to my work (edition of 1854), and in this he 
e boundless credit undeserved, and is quite anal to the 
various authors who are real sources of the information. But 
to such men as Mous, Harprneer, Naumann, Rose, von Kosert, 
‘Hausmann, Breirnaupt, saat Puitures, Mitter, DesCuor- 
ZEAUX, and many others. 
Prof. Hinrichs says in § 251: 
Finally, it is remarkable how almost entirely the RCI and 
RO R203 species belong to the tesseral system; in spite of the 
fact that Dana’s antiquated formulas represent the first of these, 
PeCl,,as PbCl. 
If we examine the hexagonal forms more closely in relation to 
their axes we fin 
WE Den OU TO TT Tasos 1 a eos g 
eeepc 6 13°C. 0 40° 7 Tl dk 
so that the 31 species (all the hexagonal minerals, except the sili- 
cates and hydrates) represented are very unequally distributed. 
They form three groups; that of Apatite, of Calcite, and of the 
Elements, 
And in § 329: 
“The normal form of the deltoid (in the Calcite group) is a rhom- 
bohedron of 104° 29’, or an octahedron with the axes 2: y:z= 
73:1 /3.” id 
The sentence about “antiquated formulas” is a fair exhibition 
of the spirit of the writer. I pass it without remark, except to say 
that the formula which he substitutes is, in chemistry, of later 
origin than my boo. 
ehng the Mineralogy, on page 198, I have the Hexagonal —— 
anged, with their angles, in a table. The table is divided in 
Bastions’ like the others, according to the o statements of 
these angles. One section of it, fifth, is that of Calcite, another, 
the fourth, is that o of the Elem and i in one of the other t 
occurs A patite, Of these shn6el z 5 Se that the third is related to 
the fourth, the rhombohedral angle being equally near 90° and but 
a little above inste og of si low 90°; oe that the second, which 
_ I farther state ye ‘Nike basal angle of pyramid 1 in the Cale . - 
section is near 90°; and hence R: R in Calcite, etc., is near 105°, 
