The well-known Treatise on Harmony, by Alfred Day, M.D., has already been prominently brought under the notice of this Association at least three times :—first, by Mr. Charles E. Stephens, in his paper entitled, “The Fallacies of Dr. Day's Theory of Harmony, with a brief outline of the Elements of a New System,” read during our First Session, 1875; secondly, by Mr. Gerard F. Cobb, M.A., whose paper on “Certain Principles of Musical Exposition, considered educationally, and with special reference to current systems of Musical Theory,” occupied our attention for two consecutive meetings of the Tenth Session, 1883–4; and lastly by Mr. Ebenezer Prout, B.A., whose paper on “Some suggested Modifications of Day's Theory of Harmony,” read as recently as the fifth meeting of the present (Fourteenth) Session, must be still fresh in our minds.