250 
Monpay, June 1Iru, 1855. 
GEORGE PETRIE, LL. D., Vicz-PresipEent, 
in the Chair. 
Sir Wriuiam R. Hamitton commenced the reading of a Pa- 
per on some symbolical extensions of quaternions, and espe- 
cially on a theory of associative quines. 
2. Sir William R. Hamilton also commenced an account 
of some geometrical applications of his theories, especially as 
founded on the notion of the anharmonic quaternion, and as 
leading to an enlarged conception of involution, not merely in 
one plane, but on a sphere, and generally in space. 
Dr. Allman drew the attention of the Academy to a peculiar 
organic production, forwarded by Dr. Harvey from Western 
Australia. Its nature is very obscure. Microscopical examina- 
tion reveals a structure which would appear to indicate the 
true relations of the production in question to be with the 
alge, and Dr. Allman, therefore, preferred placing it provi- 
sionally in this group. He named it, in accordance with the 
suggestion of Dr. Harvey, Callwellia insignis. 
The following donations to the Museum were presented : 
1. A leaden avoirdupois pound weight, found near May- 
nooth. It is stamped with the letters I + S, surmounted with 
a crown: presented by His Grace the Duke of Leinster. 
2. A very beautiful stone ring found at the bottom of a 
heap of stones, called a Danish fire-place, or lime-kiln, in the 
townland of Muckross, county of Fermanagh, in May, 1855: 
presented by F. W. Barton, Esq. 
3. A bronze brooch, retaining portions of white and red 
-enamel: presented by Rev. Charles Graves, D. D. 
