Castle in the Stars: The Space Race of 1869 by Alex Alice, translated by Anne Smith and Owen Smith, 64pp, RL 4

Aether, a concept originated by Socrates, is the element that scientists, politicians and royalty are seeking in 1869 in the hopes of harnessing its power, for good and bad. As Castle in the Stars begins, Claire Dulac is preparing to ascend 11,000 meters into the atmosphere with a light bulb designed to detect aether, her husband Archibald trying to talk her out of this crazy experiment, her son Seraphin looking on. Claire's mission is both a success and failure.
A year later, and Seraphin is obsessed with aether, turning an assignment for his Latin class on Venus, the goddess, into an opportunity to discuss Venus the planet (not a star) and the probability that planetary conditions allow for dinosaurs to exist there, making the development of an aether-engine that can get an expedition to the planet a necessity. The story shifts quickly as word of the discovery of Claire's ship's log are sent to Archibald, along with the command that he leave for a castle in Bavaria immediately.

At Swan's Rock, Seraphin befriends Hans, a lad with a love of air travel, and his half sister Sophie, a castle servant. Together, they form the Knights of the Aether with the goal of stopping the Prussians and saving the great airship that Ludwig is having Archibald (once Archibald dissuades the king of having an orchestra pit on board) build. Book 1 of Castle in the Air ends on a moment of cliff hanging excitement that will have you anxiously awaiting Book 2 while also reading Book 1 over and over, noticing something new every time!
Source: Review Copy