[ no place ]: [ no publisher ] 1923. 529-535 pages plus grey printed wrappers. An offprint from the Journal of the Optical Society of American and Review of Scientific Instruments, Vol VII, No 7, July 1923. Folded, soiled, tears, but complete - a generally worn copy. Fair. Wraps. 
A paper discussing the theory behind a "simple mechanical contrivance" Sommerfeld proposed in a 1905 paper. The contrivance was to be built by Central Scientific Company of Chicago as a piece of experimental apparatus.
"Arnold Johannes Wilhelm Sommerfeld (German: 5 December 1868 – 26 April 1951) was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and mentored a large number of students for the new era of theoretical physics. He served as doctoral supervisor for many Nobel Prize winners in physics and chemistry (only J. J. Thomson's record of mentorship is comparable to his)." (wiki)