Time travel stories come in several flavors, mostly hinged around the paradox where someone travels back in time to kill their grandfather. I think the earliest time travel story I read was the version where any tiny change in the past irretrievably changes the course of history. It was a short story by Ray Bradbury called "Sound of Thunder," where someone accidentally kills a butterfly (of course). There's Asimov's novel End of Eternity, where time engineers intentionally change history. Finally there's Connie Willis' Time Travel stories, where historians travel into the past, always fearful of accidentally changing things, and yet it always turns out that the changes they introduce were actually part of history. Willis' most recent stories in that series, Blackout/All Clear, make clear that the universe may in fact be using the time traveling historians to make sure things go as intended.
Frank Chadwick's story The Forever Engine concerns the adventures of Jack Fargo, a former US Marine who fought in Afghanistan, but is now teaching history, trying desperately to forget the past he lived. Jack gets summoned to a small town in England where a wartime buddy of his is working on a secret weapon that apparently is also a time machine. The troubling thing is, the time machine seems to show that, somehow, the past has been changed, and the present as we know it may be on the brink of destruction! But before Jack even has a chance to look into matters, a huge explosion flings him into oblivion, and when he wakes up it's 1888, and ironclad battle ships are floating in the sky above a smog shrouded London.
The story's main characters, Jack Fargo, and Gabrielle Courbiere, the beautiful French spy, are well realized heroic figures. Jack's main motivation is making sure that the future in which his daughter exists is restored to reality. Gabrielle's motivations are far more mysterious. Since she's a spy it's not all that surprising. Still, when all is revealed towards the end of the book she doesn't suddenly pop. It's more a case of getting a new perspective on someone you thought you knew well.
Since this story's history is different from our past there isn't a good way of judging if Chadwick did his research. And since I'm no historian I don't really care all that much. We meet a few people that are known to us in the here and now, and their presence serves as a kind of anchor in a story that would otherwise have us all adrift.
I can't say more about the story without spoiling things. Jack's competences as a former Marine and history professor are both called upon repeatedly, for a series or cracking good adventures with thrills and spills. If you like steampunk I think you'll love this story, but it's a great read just from a general action adventure angle, as well.