SKETCH OF RUDOLPH KOENIG. 547 



products of his labor, but to use these in the presence of physi- 

 cists and to show practically the value of the graphic method of 

 studying harmonic motion which had grown almost to perfection 

 in his hands. The mathematical analysis of wave-motion had 

 been abundantly brought out in technical treatises. Dr. Thomas 

 Young, in the beginning of the present century, had pointed out 

 the method by which a tuning-fork might be made to trace a 

 record of its own vibrations, and his hint was put into practice 

 nearly half a century afterward by Wertheim and Duhamel. 

 But Koenig was the first to apply this method systematically to 

 the registration of not only simple vibrations but also compound 

 harmonic motion ; and a large variety of such phonograms exe- 

 cuted Avith apparatus of his device, and accompanied with the 

 tracings of the corresponding theoretical curves, attracted much 

 attention at the exhibition. The method has since been adopted 

 in a number of other fields, notably in physiology for the analysis 

 of animal motion, and in general physics for the measurement of 

 minute intervals of time. 



At the same exhibition in 1862 Koenig exhibited a wholly new 

 method of making the effects of sonorous vibration easily visible 

 by utilizing the delicate sensitiveness of flame to variations of 

 atmospheric pressure. Four years earlier some noteworthy exper- 

 iments had been made in America by Le Conte on the effect of 

 such vibrations upon naked gas-flames ; but no development had 

 thus far been evolved from them. Koenig devised the manomet- 

 ric capsule through the medium of which the pressure at the out- 

 flowing jet is modified at will by sound-waves conducted to an 

 elastic membrane. The motion of this produces pulsations in the 

 gaseous fuel, and their effect on the flame is observed by looking 

 at its image reflected from a revolving mirror. This beautiful 

 method has been applied by its originator with much success to 

 the study of the interference of sound, and to the investigation of 

 the quality of musical sounds. No two vowels can be sung in 

 succession to the delicate flame without impressing on it their 

 separate individuality ; and the eye is thus permitted to compare 

 differences which the ear may recognize but not analyze. To see 

 one's own voice in a mirror, to watch the successive phases of mel- 

 ody and harmony, to see two sounds interfering and producing 

 visible silence— these are some of the revelations of the manomet- 

 ric flame. 



This remarkable exhibition of Koenig's originality brought 

 him prominently into notice everywhere. A detailed description 

 of his work was published soon afterward by Prof. Tisko in Vi- 

 enna, and from that day to this he has had no rival in the field 

 which he had made his own. In every university where acoustics 

 is taught Koenig's apparatus is the standard. Honors also were 



