I wish to-night to lay before the members of the Musical Association some portions of the theory of musical rhythm, as explained by the late Rudolph Westphal; and with this object have chosen the Forty-eight Fugues for my subject, since their rhythmical construction shows more variety of form, and more instinctive knowledge of the possibilities of rhythm, than perhaps any other modern music. Westphal's investigations and explanations of the principles of rhythm are so important and far-reaching that they must in the near future occupy a prominent place in musical theory; the chief bars to their general acceptation being their somewhat startling novelty, and the large use he makes of unfamiliar Greek terms.