In most instruments the quality and variety of sound is so directly traceable to a difference in the way in which the motive power is applied, that it does seem but natural to suppose that the timbre of the pianoforte is amenable to similar influences. We need but listen to the first attempt of a learner to the violin, for example, to be convinced how entirely the timbre of the instrument is at the mercy of the performer; and although it is remarked commonly enough that beginners on the piano are not nearly so annoying to their hearers as those on most other instruments, still the unsatisfactory result of their first awkward attempts not unnaturally gives some colour to the very general impression that the actual tone of the piano depends upon the way in which the keys are struck. It is my belief, however, that this opinion is false, and that not only because by direct experiment I have myself failed to alter the character of the sound, unaccompanied with a corresponding change in its intensity, by any variety in the mode of striking the key which I could devise, but because a theoretical consideration of the matter must, I think, convince one of its utter impossibility. Thanks to the researches of Helmholtz, we are now provided with all the necessary knowledge of the principles which regulate the quality of the sounds of most musical instruments, and that of the piano has been clearly enough explained by him. I must not occupy your time by detailing the results of his researches—suffice it that every source of difference save one lies entirely within the domain of the manufacturer, and just as completely without that of the performer. The shape, size, weight, and hardness of the hammer; the place at which the string is struck; the density, rigidity, and elasticity of the string—all these are matters over which the player has no control whatever. The only exception to be found lies in length of time during which the hammer remains in contact with the string, in comparison with the periodic time of the prime tone. Helmholtz shows that the upper partial tones increase in intensity according to the rapidity with which the hammer quits the string after impact. He, indeed, gives a table illustrative of this for certain notes, which presents at a glance the relative intensities of the upper partials in cases where the hammer remains touching the string during three-sevenths, three-tenths, three-fourteenths, and three-twentieths of one vibration of the lowest partial, and thence demonstrates that the natural timbre of the instrument varies gradually from the lowest to the highest notes of its compass. He has not adverted to the fact that the quickness of rebound in the hammer must depend upon the force with which the key is struck, nor upon its consequence, that increased richness in the upper partials will therefore be accompanied by an increase in the loudness of the sound.