104 Mr Brooke’s Remarks on Dr Brewster s Reply 
whatever they may, which would singly have produced theperfect 
pyramid, or the perfect prism ; and his trapezoidal outlines may 
aW be referred to an analogous cause. Dr Brewster allows that 
some of the Faroe crystals have not the tesselated structure, — a 
fact which is not at variance with the preceding conjecture. 
I have just measured several crystals of the apophyllites from 
Faroe, Uto, and Fassa, and have found them agreeing remark- 
ably in the inclinations of their corresponding pyramidal planes. 
If we denote the two adjacent pyramidal planes of Dr Brewster, 
Fig. 7. PI. I. Vol. I. of this Journal, by a and a the square 
terminal plane by P, the measurement may be given thus : 
Fa^oe. 
a on a' — 104° 6 to 8' 
a on P, is consequently 
a over P, on a, 
Uto . Fassa. 
104° 10' ' 104° T to 10' 
119 38 nearly. 
59 16 
I can feel no hesitation, therefore, in saying, that the Tesse- 
lite agrees, crystallographically, with the Apophyllites from Uto 
and Fassa ; and, as we have seen that its chemical composition is 
also similar, it cannot, I think, be ranked as a distinct species. 
On the crystalline form of the Sulphato- tri-carbonate of Lead, 
I have nothing” to offer in addition to what I have stated in a 
separate article in the present Number of this Journal. 
I may refer here to a circumstance alluded to in p. 370 , 
No. XVIII. of this Journal. Dr Brewster says, u The minerals 
of the Zeolite Family having been particularly examined by Mr 
Brooke and myself, we have had occasion to apply our respective 
methods of observation to several minerals which had not been 
carefully studied by preceding mineralogists. Two of these 
minerals were the Nadelstein of Faroe , and a mineral from 
Aix-la-Chapelle , supposed by Flaiiy to be a Stilbite. All the 
resources erf' crystallography in the hands of Mr Brooke were 
unable to distinguish these minerals from those already known. 
I have determined both of those to be new minerals ; and the 
accuracy of these determinations has been completely established 
by chemical examination.' 1 '' 
The part of this quotation which relates to me is altogether 
without foundation. The only specimens of the Faroe nadel- 
surfaces, and where the external form of the latter deposites differs from that of the 
included crystal- 
