In 1855 I accepted as pupils some four or five young ladies who were being educated at a fashionable boarding-school in New York. One of these girls was very bright and intelligent but without special musical talent. She was extremely averse to application in study, and the problem for me was to invent some way by which mental concentration could be compelled, for from the moment she sat down to the piano to practise she was constantly looking at the clock to see if her practice-hour was up. After a little study I found that in playing a scale up one octave and back, without intermission, in 9/8 time, there are necessarily nine repetitions of the scale before the initial tone falls again on the first part of the measure. Thus, [Illustration: musical notation] and so on until another accent falls upon the initial C. Such an exercise is called a rhythmus, and the repetitions compel mental concentration just as surely as the addition of a column of figures does. I found that if the compass was extended four octaves, thus, from [Illustration: musical notation] the nine repetitions of the scale would require from three to four minutes if played at a moderate rate of speed. I saw at once that a state of mental concentration could not be avoided by the pupil, and that in this exercise lay a basic principle. I gave the exercise to my pupil. The result was that when the next lesson-hour came around and I asked her how she found the new exercise, she exclaimed: "How do I like it? Why, you have played a pretty trick on me! It took me nearly an hour to accomplish it; but I like it. Why did you not give it to me before!" "Because," I said, "I invented it simply in order to compel your attention to your work." Following up the principle of grouping the tones, I applied the rhythmic process not only to all sorts of scale passages, but included in the treatment arpeggios, broken chords, octaves, and in fact all passages idiomatic of the pianoforte. The work of amplification was readily accomplished, and the result was a complete method in which for the first time, so far as I am aware, scientific rhythmic treatment was elaborated. This "Accentual Treatment of Exercises," as I called the system, was first published in the Mason & Hoadley Method, New York, 1867. The importance of accentual treatment is now recognized in every modern method.