Hagenow String Quartet - reside in Nebraska area, article from The Courier Nebraska 13th February 1897. The article titled "Musical Mention" by John Randolph. I believe Hagenow String Quartet may be one of top amateur ensemble, good enough to received a large portion of local newspaper story. No internet result from search "Hagenow String Quartet" , it's a surprising result indeed.
However when searching August Hagenow + violin , some results come to light:
Mr. August Hagenow: August Hagenow came to Lincoln from Chicago in 1886; he was a violinist, but also conducted bands and orchestras in Lincoln. He joined the faculty of O. B. Howell's Nebraska Conservatory of Music in 1889, the same year he married Emma S. Seifert. In January 1894 he opened the Hagenow School of Music, but was bought out by Willard Kimball of the University School of Music in June 1894. Hagenow joined the faculty of the University School of Music, becoming director of the university band from 1903 to 1911. http://cather.unl.edu/j00085.html
Interesting passage from the article :
In the spring of the year 1889 a few musicians were in the habit of meeting from time to time to spend a musical evening in the practice of string quartets and other music. From the embryo was developed the Hagenow String Quartet consisting at that time of Mr. August Hagenow, first violin, Charles Hagenow, 2nd violin, Mr. G. Sayer, viola, and Dr. E. George Andrews, cello. At the time the quartet was organized public were hardly thought of, the only object being the pleasure derived from the ensemble playing.
Hagenow String Quartet story in The Courier, 13th Feb 1897