It may be in the remembrance of some now present, that about two years ago I had the honour of bringing before the Musical Association a short paper on brass wind instruments, in which I endeavoured to demonstrate the effects produced by variations in the forms of tubes upon the positions of the nodes of sound-waves generated in such tubes, and consequently upon the sequence of proper tones and correctness of intonation. The summary of the matter then brought forward was this: that a brass instrument is a tube closed at one end, of such a form as to give the series of intervals producible from an open, and not from a closed cylindrical tube, such form being neither a common cone, nor a conic frustrum combined with cylindrical tube. At the conclusion, attention was drawn to the fact that quality of tone was intimately associated with the points then under consideration; and it is to this subject of quality of tone that I have ventured to ask your attention this afternoon.