It is true that all of these stories, like most of Davidson's fiction, have a distinctly old-fashioned setting or slant--Davis says in the Afterword, "Avram Davidson was often a time traveler into the past.... The old, the archaic, the antique fascinated him"--but still picky me can't help but note that rather few of the stories are actually set in the 19th century, historical or alternate. Picky me. As to the content of those stories, it's pretty accurately conveyed by the subtitle once it has flipped out: "Truthful Accounts of Living Fossils, Montavarde's Camera, The Irradiodiffusion Machine, and El Vilvoy de Las Islas; with Heinous Crimes, Noble Ladies in Adversity, Brilliant Detections, Imperial Eunuchs, Political Machinations, etc., etc." Slightly different, but especially interesting in its way, is the final story, a 'ghost-novel' sketched in by Michael Swanwick, which demonstrates how "nothing ages so fast as science fiction."
You either like Davidson's style--very chatty, very learned, very eccentric, lots of playing with language and with dialect--or you don't. I do, but even I advise reading these stories one at a time rather than wolfing down too many in a sitting; assume some metaphor about how eating too many savoury treats at once, however small, however spicy, is bad for the digestion.