The Knights of Electricity - The Bigelow Diaries, #1

Manhattan, NY 1891A new mechanical age has dawned, driven by the power of steam and electricity. With this new world, come wonders and dangers. A group of young scientists known as the Knights of Electricity was going to use this power to change the world. Instead, it changed them. Abraham Tiberius Bigelow, a genius with no equal, is the lone member of the Knights, still working for the betterment of man.
Elizabeth James is a cowgirl from the Badlands, more accustomed to wrestling steers and fighting gunmen than flying in dirigibles. A new threat has appeared and as the two rush to face it, they find themselves confronted by the unthinkable... a new enemy, one who refuses to die.