Koenig, Karl Rudolph

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Koenig, Karl Rudolph

(b. Königsberg, East Prussia [now Kaliningrad, R.S.F.S.R.], 1832; d. Paris, France, 1901)


Koenig’s father was on the faculty of the University of Königsberg. He took his Ph.D. in physics there and studied with Helmholtz, although at that time the latter was not primarily interested in acoustics. Upon completing his studies, koenig mobed to Paris in 1851 to become an apprentice to Vuillaume, one of the most famous violin makers of the time. Upon completing his apprenticeship in 1858 Keening started his own business as a designer and maker of original acoustical apparatus of the highest quality. For the remainder of his life he produced equipment used for acoustical research throughout the world and renowned for the precision and skill of its workmanship. Every piece of equipment was tested by Koenig himself and usually employed in his own basic researches before it was sold. Much of the fundamental research in acoustics before the advent of modern electronic methods was done with Koenig’s equipment; and even today Koening organ pipes, tuning forks, and other apparatus are still used. Koening never developed a large and lucrative business, preferring to produce instruments to be sold to scientists who he knew would appreciate their precision.

At the London International Exposition in 1862 Koening displayed his equipment, including his new manometric-flame apparatus. For this he was awarded a gold medal, a recognition which first attracted wide public attention to his apparatus. Koenig went to Philadelphia in 1876 to exhibit a large collection of his acoustical apparatus at the centennial Exposition. His exhibit was given the highest rating by the awards committee, and he received another gold medal. His hopes of developing business relations in the United States were not realized, however; and despite the efforts of Joseph Henry and other influential American scientists, Koenig’s equipment was not sold. Finally, a part of the extensive collection was purchased by subscription and presented to the U.S. Military Academy at West Point. Another part of the Philadelpohia exhibit was purchased by the University of Toronto for research work, and the remainder was ultimately returned to Paris—to Koenig’s great disappointment and financial loss.

One of Koenig’s most famous instruments was the clock tuning fork used to determine the absolute frequency of sound sources by direct reference to a standard clock. It employed a variable-frequency tuning fork of sixty-two to sixty-eight vibrations per second, which served the clock escapement much as the pendulum does in an ordinary clock; and by comparing the rate of the Koening clock tuning fork with that of an unknown sound, the latter’s frequency was determined. This instrument was of great accuracy and was employed in many important researches in acoustics. Koening himself used his clock tuning fork to establish in 1859 the standard of pitch for music known as the “diapason normal.” This was adopted in 1891 as the international pitch of A = 435 cycles per second. A pioneer in the graphic recording of sound, Koening greatly improved the phonautograph invented by Leon Scott in 1857. The method was to focus sound through a horn onto a diaphragm attached to a stylus, thus producing a visual record of the sound wave on a revolving drum. This instrument and method were well known to Edison in his work on the phonograph, invented in 1877, although there is no specific reference to Koenig’s pioneer invention.

Koening developed special acoustical apparatus for the study of vowels, for the analysis of tone quality, for the synthesis of speech sounds, and for many other acoustical studies demanding high-precision measurement. His largest tuning forks were eight feet long with resonators twenty inches in diameter. One of Koenig’s precision tuning forks was used by Albert A. Michelson in a stroboscopic comparison to determine precisely the speed of the revolving mirror used in his measurements of the revolving mirror used in his measurements of the velocity of light at Case School of Applied Science in 1882-1884.

In addition to producing precision instruments for other workers in acoustics, koening conducted important fundamental research. His achievements include studies of the physical characteristics of vowels, the nature of tone quality in sound, the effect of the phases of the several components of a complex sound on tone quality, the nature and characteristics of combination tones, and the frequency limits of audibility of sound. In 1882 he published a number of his researches in a book entitled Quelques expériences d’acoustique, which summarizes scientific work that had appeared previously in Annalen der Physik and in Comptes rendus hebdomadaires des séances de l’ACadémie des sciences.

Koening was a lifelong bachelor and lived in the same apartment in which he built his equipment and carried on his researches, located on the Quai d’Anjou, facing the Seine on the Île St. Louis. This was one of the quietest places in Paris, where he could carry on his acoustical work under ideal conditions. The walls of his rooms were lined with tuning forks, resonators, and other apparatus. Koenin contributed a great deal to the development of the science of sound during the nineteenth century. Primarily an experimentalist and instrument maker, he was a man of great intellectual power with a deep physical understanding of the nature of sound and music. His attention to detail was phenomenal, and the quality of his finished “apparatus was superb. Some of Koenigs finest equipment is now maintained” in Conservatoire des Arts et Métiers in Paris, a fitting memorial to his great contributions to the science of acoustics.


Among Koenig’s most important works are Quelques expériences d’acoustique (Paris, 1882): and an article in Comptes rendus hebdomadaires des Séances, de I’Academie des Sciences, 70 (1870), 931. There are also articles in the following issues of Annalen der Physik:146 (1872), 161; 9 (1880), 394-417; 57 (1896), 339-388, 555-566; and 69 (1899), 626-660, 721-738.

Robert S. Shankland

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