105 
mittent in visibility, that which was opposite to the left hand 
of the spectator being the most so. 
After 11 o’clock the appearance became more and more 
obscure, until the cross was replaced by an obscure blur. ‘The 
paraselenz also disappeared, while the halo, though diminished 
in brightness, continued some time longer. 
June 9, 1845. 
CAPTAIN LARCOM, R. E., Vice-President, in the 
Chair. 
James Claridge, Esq., Adolphus Cooke, Esq., Windham 
Goold, Esq., Charles Croker King, M. D., and Charles Wye 
Williams, Esq., were elected Members of the Academy. 
Mr. Richard Sharpe read a notice of a new electric clock, 
on the principle of Mr. Wheatstone’s telegraphic instruments. 
The Rev. Charles Graves made a further communication 
relative to Algebraic Triplets, and their Geometric Inter- 
pretation. 
Besides the system of algebraic triplets developed in former 
communications to the Academy, Mr. Graves has conceived 
another, which appears to admit of an interpretation in some 
respects more closely analogous to Mr. Warren’s geometrical 
representation of imaginary quantities. 
As the symbol Y —I may be taken to indicate a rotation 
in the plane of x from the axis of z to the axis of y, it seems 
natural to conceive another symbol representing a rotation in 
the plane of wz, from the axis of x to the axis of z. The re- 
petition of either of these operations would reverse the direc- 
tion of a right line originally placed on the axis of a: and 
VOL, Il. I 
