Page:Popular Science Monthly Volume 73.djvu/83

Rh and power were joined to scientific competence. I, therefore, leave them for a moment to take a glimpse—it can be no more—at the strictly scientific interest as we see it illustrated in Johannes Müller's greatest pupil, Helmholtz (1821-1894).

Helmholtz ranks not simply with the foremost scientific intellects of the nineteenth century but with the master minds of all time. His range, grasp and insight combined to render him monumental. A contributor to at least eight sciences—physics, physiology, mathematical physics, meteorology, medicine, chemistry, anatomy and esthetics, in three of them he stands high among the foremost. More than this, as Volkmann has recalled, "one of his chief merits was to establish a harmony between the vast accumulation of facts that characterized the period comprehending the middle of this century and the more theoretical studies." Besides, he possessed unusual manipulative skill, his inventions of the ophthalmoscope and ophthalmometer alone would have assured any ordinary reputation. Above all, he was a humanist, being an accomplished musician, an art critic, and acquainted with the trend of philosophical thought. His discoveries of classical grade amaze one by their thoroughness and versatility. The conservation of energy; the mechanism of the lens of the eye in relation to accommodation; the movements of the eyeballs with the attendant problems of binocular and stereoscopic vision; the profoundest questions of hydrodynamics, thermodynamics and electrodynamics, the last culminating in the revelations of his favorite pupil, Heinrich Hertz; the axioms of geometry; the dark places of meteorology; the deeps of physiological optics and of mathematical physics, all bear witness to his profound, masculine and subtle intellect. But, for our present study, the palm must go to his long struggle with the difficulties of sensation and perception. These absorbed his principal attention from 1852 till 1867 and, in a lesser degree, till his death. He laid the foundation characteristically by his inquiries into the rate of nervous impulse in the motor and sensory nerves, about 1850, and his first paper, on sensation proper, followed in 1852. These labors were crowned magnificently by the publication, in 1863, of his "Sensations of Tone," and, in 1867, of his "Physiological Optics"—masterpieces both. The former, which involved the most complicated research, has earned the title, "the Principia of acoustics," and must be studied long to be appreciated. For, it not only ranged over the entire subject but, incidentally, raised important problems that belong elsewhere, especially to the domains of phonology and esthetics. Questions about the quality of the human voice and the absolute pitch of vowel sounds lead us away from the physical and the physiological laboratory to a very different environment. Similarly, the "Physiological Optics," with