54 6 THE POPULAR SCIENCE MONTHLY. 



practical optician was only less remarkable than his genius as a 

 mathematician. Herschel practiced music as a profession, while 

 giving all his spare time to the grinding of telescope mirrors and 

 to observational astronomy. Ruhmkorff wandered to Paris as a 

 boy of sixteen, and became a porter in the laboratory of a French 

 physicist. In time his name became known wherever the induc- 

 tion coil is used, whether in the investigations of the physicist or 

 in the operations of commercial electricity. Wheatstone adopted 

 the vocation of a maker of musical instruments in preference to 

 grinding Greek and Latin verses at school. This work he contin- 

 ued for many years, achieving world-wide distinction as an original 

 investigator in acoustics, and afterward in optics and electricity. 



Younger than Ruhmkorff and Wheatstone, but amply worthy 

 of being classed with them, is Rudolph Koenig, the most distin- 

 guished living inventor and mechanician in the domain of acous- 

 tics. He was born on the 26th of November, 1832, in Koenigs- 

 berg, Prussia. His father was teacher of mathematics and 

 physics in the city gymnasium, where the son as pupil received 

 the usual high-school training, corresponding in some particulars 

 to the academic work in most American colleges. He exhibited 

 much aptitude in physics as well as music ; but, being compelled 

 to depend upon his own resources, he went to Paris at the age of 

 nineteen years, to devote himself to the construction of stringed 

 instruments. Here he worked for several years under the direc- 

 tion of the celebrated violin-maker Vuillaume, but at the same 

 time devoted such leisure as he could command to the study of 

 mechanics and physics. 



Quite naturally acoustics was the branch of physics which 

 presented most attraction to the young mechanician, and in time 

 it claimed his almost undivided allegiance. Meanwhile his suc- 

 cess was such as to warrant him in undertaking business on his 

 own account, so that in 1858 he fitted up a working place for the 

 construction of acoustic apparatus, and in 1859 he issued his first 

 catalogue, containing descriptions and illustrations of the various 

 instruments made by him. Some of these were improvements 

 upon instruments already in use, but many were new, the out- 

 come of Koenig's own ingenuity. This catalogue formed the 

 basis of the subsequent expansions which appeared in 1865, 1873, 

 1882, and 1889. The last is a volume of one hundred pages, with 

 descriptions of two hundred and seventy-two instruments, in 

 French, English/and German, and including probably everything 

 that is employed in modern acoustic investigation. 



It was in 1862 that Koenig began to be known to the scientific 

 world as an investigator. An International Exhibition was held 

 during that year in London, and the indefatigable instrument- 

 maker was present, not merely for the purpose of displaying the 



