After various searches through Herman Conrad's family tree, I was finally able to locate a living descendant of that great tubist who was the first to play the Sousaphone. His name is Daniel Corry, and he is Herman's great-great grandson (Daniel's father was Christopher, whose mother was Henrietta Alice Conrad, whose father was Edward Columbus Conrad, whose father was Herman).
As it turns out, Daniel lives within a few hours of me, so we connected this past Saturday and had a marvelous time! I was able to share the whole story of his great-great grandfather, of whom he was unaware, and we made a trip out to the J. W. Pepper headquarters, in Exton, PA, where Daniel was able to play the historic horn that Herman was the first to play 121 years ago:
And just for kicks, here's a side-by-side of Herman, 1895, and Daniel, 2016:
