When, at the beginning of the present session, I promised our Secretary to read a paper before this Association on Dr. Day's System of Harmony, I ventured to indulge the hope that the chair would be taken on that occasion by the eminent musician to whose efforts we are indebted for the most complete exposition of that system. By the sudden and lamented death of Sir George Macfarren, England has lost her greatest theoretical musician; and his name is so intimately connected with the subject on which I am to have the honour of addressing you this afternoon, that I cannot refrain from paying this tribute to his marvellous gifts, and of acknowledging my own indebtedness to his writings for a more thorough insight into what I believe to be the true theory of music, than I had been able to obtain from other sources.