The Ghost of the Revelator by L. E. Modesitt

I think I finally figured out where the first divergence point was in Modesitt's alternate history stories of Johann Eschbach, begun in Of Tangible Ghosts. Hook baited...I ain't tellin'.

In Ghost of the Revelator Modesitt continues the tale of Professor Eschbach and his lovely bride, Lysette. The political intrigue continues, as rival factions within the nation of Columbia and the insidious spies from the nations of Deseret, New France and Austro-Hungary try to gain control of the "ghosting" technology discovered in OTG.
 
Lysette's singing career finally begins to take off, now that she has become a citizen of Columbia through marriage, and she is invited to sing for the president, then to teach and sing in a concert series in Deseret.
Though Modesitt paints a rich tapestry of everyday life in this alternate timeline, the story tends to drag. Action scenes are few and far between. Modesitt also seems to expect us to remember all the political machinations and motivations from the first novel, and it's been a while since it came out. I'd suggest reading the two one sitting, so to speak.
 
Since I haven't kept up with the sf magazine scene in a long time, I may be unaware of its existence, but it seems that there's an untold story of the good professor's previous life that would provide some keys to his motivation and his character in these novels. If you've run across the story somewhere, let me know, so I can catch up.