BY E. J. BENNETT, ESQ. PK 
EXPLANATION OF PLATES. 
Plate V.—The Cataract—see 1st paragraph. 
Plate VI.—Effect, due to the presence of the particular Cataract 
depicted, in viewing printed matter or simliar object 
with both eyes. 
On the motion of Mr. D. O’Connor, a vote of thanks was 
unanimously accorded to Mr. N. Bartley and E. J. Bennett, 
insomuch as, though non-members, they had written valuable 
papers for the Society. 
NOTE ON EE OCCURRENCE OF 
PRICLINIC KT EL SPARS Ny kik GRAM Tie 
OF CHARTERS, TOWERS. 
BY 
A. W. CLARKE, Government Mineralogical Lecturer. 
) g 
(Read on 14th October, 1887.) 
THIS note comprised the substance of a letter to the honorary 
Secretary, and was read by him in the absence of its author. 
Mr. Clarke, in his endeavour to determine the origin of the 
auriferous calcite of the Charters ‘Towers goldfield, had been led 
to examine the granites to be met with there and their constituent 
minerals, and amongst the latter the felspars. Of these last was 
one which, when suitably prepared and viewed with the polari- 
scope, displayed precisely similar optical characters to those 
afforded by the triclinic felspars which occurred in felsite porphyry 
from Germany. ‘This was seen on comparing two illustrations 
forwarded by Mr. Clarke and representing :—1. A drawing showing 
the appearance, as observed by the use of the polariscope, of a 
section of felsite porphyry which contained triclinic felspar, and 
which had been prepared by Fuess, supervised by Professor 
Rosenbach. 2. A drawing derived in a similar manner from a 
section of Charters Towers granite, prepared by Mr. Clarke 
himself. Further, the author had analysed a portion of the stone 
from which his section had been cut, and in 15.43 grains had 
