54 
mission to read the present paper, Sir William R. Hamilton 
had kindly communicated to him the abstract and the proof 
sheets of a memoir by Professor De Morgan, on Triple Al- 
gebra. That paper contains the discussion of a system of 
triplets, which is most closely connected with the one now 
proposed: the only difference being that Professor De Mor- 
gan uses what arein fact new imaginary cube roots of negative 
unity. 
Mr. Graves thinks that in the interpretation and generali- 
zation of his results he has met with greater success; but he 
fully concedes to Professor De Morgan the prior possession 
of what must be looked upon as fundamental in this theory, 
the conception of symbols which act upon each other in the 
same manner as the imaginary cube roots of unity. Mr. 
Graves also stated that his brother, John T. Graves, Esq., 
had anticipated him in the idea of using cube roots of positive 
unity in the constitution of algebraic triplets. - 
The remaining portion of the paper, having reference 
chiefly to the interpretation of the formule obtained in the 
multiplication of triplets, was postponed until the next meet- 
ing of the Academy. 
Mr. George Yeates presented a tabular Return of the Ob- 
servations made by him with Barometer, Thermometer, and 
Rain Gauge, at his residence, near Portobello, County of 
Dublin, during the year ending 31st December, 1844.—(See 
Appendix, No. 11.) 
DONATIONS. 
An Essay on Aerial Navigation. By Joseph M‘Sweeny, 
M.D. Presented by the Author. 
Archeologia, Vol. XXX., and Index to Vols. XVI. to 
XXX., inclusive. Presented by the Society of Antiquaries 
of London. 
J. H. R. Mott’s Advice and Instructions for playing the 
