An epoch-making work which led the way to the acceptance of the fundamental physical doctrine of the conservation of energy.

Helmholtz showed the muscles to be the principal source of animal heat.

Helmholtz succeeded in measuring the velocity of the nervous impulse, by applying the knowledge and techniques of ballistics to the problem. In 1852, using a pendulum-myograph of his own invention, he measured the duration of an electric current through a galvanometer from the moment the nerve was stimulated to its interruption when the muscle contracted. A more detailed report “Messungen über den zeitlichen Verlauf der Zukkung animalischer Muskeln und die Fortpflanzungsgeschwindigkeit der Reizung in den Nerven”, appeared in the same journal volume, [276]-364, with its second part in the volume for 1852, 199-216.

Invention of the ophthalmoscope, one of the greatest events in the history of ophthalmology. English translation by T. H. Shastid, Chicago, Cleveland Press, 1916.

Helmholtz determined the optical constants and explained the mechanism of accommodation, with the help of the ophthalmometer which he had invented in 1852.

Helmholtz’s theory of hearing, upon which all modern theories of resonance are based. This exhaustive study of acoustics ranks as one of the greatest books on the subject and shows that Helmholtz was, besides being a great physicist and physician, an accomplished musician. English translation of 3rd edition, London, 1875.

Includes Helmholtz’s revival of the Young theory of color vision. English translation by J.P.C. Southall of 3rd German edition, 3 vols., Menasha, Wis., 1924-25.

Helmholtz’s study of the mechanism of the tympanum and ossicles of the middle ear did much to elucidate the phenomenon of audition. It includes a description of “Helmholtz’s ligament” of the malleus. Separate offprint, Bonn, 1869. English translation, London, 1873.