530 
Proceedings of the Boycd Society 
4. Note on a large Crystal of Calc-spar, found in Lough Corrib 
by Professor Tait. By the Abbe Kenard. 
The crystal of calcite found by Professor Tait presents very large 
dimensions for a specimen, with very simple, and, at the same time, 
very definite forms. This crystal shows the faces of the primitive 
rhombohedron of 105°, and is twinned with parallel axes. The two 
individuals which compose the crystal show the form of the cleavage 
rhombohedron P (lOll); they are applied to each other with sym- 
metrical development with reference to the base oP (0001), and 
present the appearance of a simple crystal, although formed of two 
distinct halves, of which the upper belongs to one crystal and the 
lower to the other, the two individuals being complementary to each 
other. Along the twinning plane may be noticed a series of very 
regular grooves, which indicate a repetition of the twinning following 
the base, It must be noticed that the six faces do not present the 
same physical characters — two of them, the primitive faces of the 
crystal, are smooth ; the other four, although having the same crystal- 
lographic sign, are faces of cleavage more brilliant than the others. 
They appear to show that the crystal, although found isolated by 
Professor Tait, was formerly attached. This is further demon- 
strated by the presence of irregular faces, which are not amenable to 
any mathematical law. These false faces may be seen on the 
superior and inferior portions of the crystal ; they are granular, and 
without lustre, and cannot be confounded either with the crystal 
faces or with those of cleavage. They have been produced by the 
pressure exerted upon the crystal by the neighbouring crystals, which 
were developing at the same time. This consideration explains the 
anomalies which they show, when regarded from a geometrical poiiit 
of view. 
PKIVATE BUSINESS, 
Mr George M. Low, Dr Frederick Hungerford Bowman, the Eev. 
Dr J. Gordon Macpherson, M.A. ; Mr Charles Scott Dickson, advo- 
cate ; and Mr Pobert Traill Omond, were balloted for, and declared 
duly elected Bellows of the Society. 
