He used a spherical Helmholtz resonator resounding to the tone to be measured.
For cells in which the electromotive force varies with temperature, the full equation given by Gibbs and Helmholtz has also been confirmed experimentally.
The second is termed by Helmholtz the difference tone, and the third the summation tone.
Later in the same year he became assistant to Helmholtz in the physical laboratory of the Berlin Institute.
When Pasteur in 1857 showed that the lactic fermentation depends on the presence of an organism, it was already known from the researches of Schwann (1837) and Helmholtz (1843) that fermentation and putrefaction are intimately connected with the presence of organisms derived from the air, and that the preservation of putrescible substances depends on this principle.
Von Helmholtz devised a tangent galvanometer with two coils.
It may, however, be stated here that certain experiments of Helmholtz appear to show that the epoch of the harmonics has not much effect on the quality.
Von Helmholtz treats the theoretical aspects of sound in his Vorlesungen fiber die mathematischen Principien der Akustik (1898), and the physiological and psychical aspects in his Die Lehre von den Tonempfindungen (1st ed., 1863; 5th ed., 1896), English translation by A.
Thus Helmholtz explains the jarring and braying which are sometimes heard in bass voices.
Thus Helmholtz from certain observations (Sound, ii.