So: The history of hot air balloons is amazing and hilarious. I first heard about it in The Age of Wonder and was sufficiently delighted by its anecdotes of deadly ridiculousness that I vowed to include an aeronaut in the Society, even if that inclusion was super funny only to me. There are stories about the first mile-high club (an invention prioritized over the invention of basic steering, if I recall) and balloons that were more or less designed to catch on fire (or at least, it was such an inevitability that the pilots carried wet sponges with them) but I can't cite them very easily because I had the audiobook version, and finding all that stuff would be kinda hard. Sorry, that is lazy of me. Most of the professions in the Society are based on theories that could never work in real life (unless you stretch it--saying that Jekyll's neoalchemy is just weird chemistry, for instance), but not Dr. Bryson's. He's just a regular old aeronaut, because aeronauts were weird as shit and you don't really need to make them stranger to fit into this storyverse. His abilities are a bit Méliès-y, though--he can use his balloon to float up into an ether-y space and explore the stars. I expect his real-life counterpart would be horrified by this sort of unscientific stuff.