Midsummer Moon by Laura Kinsale

Ransom Falconer, Duke of Damerell, is sent to see if Merlin Lambourne, the famous inventor, has created a truly magnificent innovation that can be used in the war against Napoleon. What Ransom doesn’t realize is that Merlin is a woman, and not everyone wants to see her invention become a reality. Merlin Lambourne is a brilliant yet slightly eccentric scientist whose dream is to build a flying machine. Nothing can distract her from her goals, and Ransom offers her refuge at his estate-a safe haven to work on her invention undisturbed. But when Merlin’s dream puts them both at risk, Ransom must overcome his own fears and realize… Read more.