Prof. Mayer has turned his valuable researches in acoustical science to æsthetic uses, and criticises the present mode of arranging orchestras, the defects of which he proves by experiment. He took an old silver watch, beating four times a second, and caused it to gain thirty seconds per hour, so that every two minutes its tick coincided with the tick of an ordinary spring balance American clock, also making four beats the second. The latter was placed several feet, and the watch two feet, from the ear. In this position the ticks of the watch were lost for _nine seconds_, about the time of coincidence. The tick of the watch disappeared, "with a sharp _chirp_, like a cricket's, and reappears with a sound like that made by a boy's marble falling upon others in his pocket." This experiment shows most effectively that one sonorous impression may overcome and obliterate another, but to do so it must be more intense and of lower pitch. If of higher pitch, it cannot neutralize the other sound, however much the first may exceed the latter in intensity. This discovery, Prof. Mayer thinks, is, "next after the demonstration of the fact that the ear is capable of analyzing compound musical sounds into their constituent or partial simple tones, the most important addition yet made to our knowledge of hearing." High sounds cannot obliterate low ones, but, on the contrary, the sensation of each partial tone of which compound musical sounds is formed is diminished by all the tones below it in pitch. These discoveries he applies to orchestration as follows: "In a large orchestra I have repeatedly witnessed the complete obliteration of all sounds from violins by the deeper and more intense sounds of the wind instruments, the double basses alone holding their own. I have also observed the sounds of the clarinets lose their peculiar quality of tone, and consequent charm, from the same cause. No doubt the conductor of the orchestra heard all his violins ranged as they always are, close around him, and did not perceive that his clarinets had lost that quality of tone on which _the composer_ had relied for producing a special character of expression. The function of the conductor seems to be threefold: First, to regulate and fix the time. Second, to regulate the intensity of the sounds produced by individual instruments, for the purpose of expression. Third, to give the proper quality of tone or _feeling_ to the whole sound of his orchestra, considered as a single instrument, by regulating the _relative intensities_ of sounds produced by the various classes of instruments employed. Now this third function, the regulation of relative intensities, has hitherto been discharged through the judgment of the ears of a conductor, who is placed in the most disadvantageous position for judging by his ears. Surely he is not conducting for his own personal gratification, but for the gratification of his audience, whose ears