From difficulties of tuning, owing to friction and other causes, the real gain of these expedients is small, and when we compare them with the natural resources we have always at command in the normal scale of the instrument, is not worth the cost. The inventor of the damper register opened a floodgate to such aliquot re-enforcement as can be got in no other way. Each lower note struck of the undamped instrument, by excitement from the sound-board carried through the bridge, sets vibrating higher strings, which, by measurement, are primes to its partials; and each higher string struck calls out equivalent partials in the lower strings. Even partials above the primes will excite their equivalents up to the twelfth and double octave. What a glow of tone-color there is in all this harmonic re-enforcement, and who would now say that the pedals should never be used? By their proper use, the student's ear is educated to a refined sense of distinction of consonance and dissonance, and the intention and beauty of Chopin's pedal work becomes revealed. The next decade, 1790-1800, brings us to French grand pianoforte-making, which was then taken up by Sebastian Erard. This ingenious mechanic and inventor traveled the long and dreary road along which nearly all who have tried to improve the pianoforte have had to journey. He appears, at first, to have adopted the existing model of the English instrument in resonance, tension, and action, and to have subsequently turned his attention to the action, most likely with the idea of combining the English power of gradation with the German lightness of touch. Erard claimed, in the specification to a patent for an action, dated 1808, "the power of giving repeated strokes, without missing or failure, by very small angular motions of the key itself." Once fairly started, the notion of repetition became the dominant idea with pianoforte-makers, and to this day, although less insisted upon, engrosses time and attention that might be more usefully directed. Some great players, from their point of view of touch, have been downright opposed to repetition actions. I will name Kalkbrenner, Chopin, and, in our own day, Dr. Hans von Bülow. Yet the Erard's repetition, in the form of Hertz's reduction, is at present in greater favor in America and Germany, and is more extensively used, than at any previous period.