ear is usually found to be a sufficient guide, and at standard temperature these are rarely if ever found to deviate by more than a fraction of a single vibration from the value stamped upon them.
Within the last year Koenig has published two important papers: the one on beat tones due to the excitement of two separate motions of vibration on the same body; the other on tones due to the composition of waves of unlike form. These papers have an important bearing on the theory of musical quality. Their author is not yet sixty years old, and it is reasonable to expect from him many more contributions to the science of acoustics before old age interferes with the acuteness of his wonderfully accurate musical ear, or diminishes his power to do good work.
The following is a list of the principal contributions of M. Koenig to science, with their dates and the names of the periodicals in which they first appeared. The titles are translated into English, and the length of each article is approximately indicated by the number of pages covered:
1. On the Application of the Graphic Method to Acoustics. (Cosmos, 1862, pp. 27.)
2. Apparatus for the Measurement of the Velocity of Sounds at Small Distances. (Comptes Rendus de l'Académie des Sciences, October 13, 1862, pp. 2.)
3. Experiments relating to Wheatstone's Explanation of Chladni's Figures. (Comptes Rendus, March 27, 1864, pp. 7.)
4. A New Stethoscope. (Poggendorff's Annalen, 1864, pp. 2.)
5. Experiments to determine the Influence of the Movement of a Source of Sound on Pitch. (Koenig's Illustrated Catalogue, 1865, p. 1.)
6. On the Fixed Notes characteristic of Vowel Sounds. (Comptes Rendus, April 25, 1870, pp. 5.)
7. Manometric Flames. (Poggendorff's Annalen, 1872, pp. 36.)
8. A Tuning-Fork of Variable Pitch. (Poggendorff's Annalen, 1876, pp. 2.)
9. On the Phenomena produced by the Concurrence of Two Sounds. (Poggendorff's Annalen, 1876, pp. 62.)
10. On the Origin of Beats, and the Beating Sounds of Harmonic Intervals. (Wiedemann's Annalen, 1881, pp. 14.)
11. Description of an Apparatus for Lecture Demonstration of Beating Sounds. (Wiedemann's Annalen, 1881, pp. 4.)
12. Researches on the Difference of Phase existing between the Vibrations of Two Associated Telephones. (Journal de Physique, May, 1879, pp. 5.)
13. Researches on the Vibrations of a Normal Fork. (Wiedemann's Annalen, 1880, pp. 21.)
14. Harmonic Vibrations excited by the Vibrations of a Fundamental Sound. (Wiedemann's Annalen, 1880, pp. 13.)
15. A Method for observing the Air Vibrations in Organ-Pipes. (Wiedemann's Annalen, 1881, pp. 12.)
16. Remarks on Musical Quality. (Wiedemann's Annalen, 1881, pp. 26.)
17. On Beats and the Beat Tones of Two Vibratory Motions excited in the Same Body. (Wiedemann's Annalen, 1890, pp. 8.)
18. On Composite Tones, with Waves of Unlike Form. (Wiedemann's Annalen, 1890, pp. 9.)
