Before resuming our subject it will be desirable briefly to mention a few points dealt with at the last meeting, just to make the position of the question clear. By “Musical Physics” we mean the science that deals with the origin of musical sounds, and their mode of transmission through the air. These sounds are conducted by the ear to the brain. So far as the stages by which they are so conducted have been brought within the range of knowledge, they are physiological; operations beyond this, the nature of which still remains unrevealed to us, we entitle psychic. It was stated, on the authority of a most eminent physiologist, that science has as yet discovered no difference whatever between the ear of the musician and the ear of the non-musician; consequently our appreciation of music is not a physiological, but a psychical problem. The question then followed: Can musical physics explain musical psychics? Do the operations of the brain in dealing with musical sounds correspond in any degree with those constant features of them which are physically demonstrable, and which form a portion of what we call the immutable laws of Nature? It was thoroughly established by quotations from the works of the Professors of music at our two oldest Universities, as well as from other sources, that there exists a strong tendency to apply these laws to explain the case, and to make them the basis of what is called musical theory. It was shown that these natural phenomena had been made the ground of special systems of chord classification, and of special chord treatment. We also found that some more or less systematic attempts had been made to trace the origin of the musical scale to the same source, and it was with an attempt to point out the difficulties in the way of any such derivation that the paper closed.