When first I was honoured by an invitation to read a paper before this Association, I shrank from the undertaking, because of the difficulty of selecting a topic upon which I might venture to discourse with any hope of interesting my hearers. But upon reflection it occurred to me that this was a difficulty which would certainly not decrease as time went on, and session after session witnessed the production of lectures on new subjects. Therefore when, at the beginning of the present session, I was again invited to read, I thought that my wisest course was to gather together some ideas without further delay. My subject suggested itself to me during the preparation of a paper on “Triads, their Relationship and Treatment,” which I read recently before the College of Organists. The title of that paper would properly have included to a great extent the subject of the present one; but I soon found it impossible to deal with the whole question within reasonable limits, and then arose the idea of taking “consecutive fifths” as the theme for a separate paper.