If The Last Man is a science fiction novel, it is one noticeably lacking in the technological gimmickry associated with the genre. (A parody of Shelley's and other's futuristic fictions, published only four years after The Last Man appeared, proves that such technological machinery was available to Mary Shelley--and makes its absence from her novel all the more obvious.) Besides medical or epidemiological science, the one technology central to the book is balloon flight. In Shelley's imagined 21st century, people travel fairly casually and over great distances by balloons (though more often they go by ship).
Balloons in the early nineteenth century were still strongly associated with the Enlightenment goals of the previous century: universal knowledge, scientific progress, and the Promethean conquest of nature by human reason. The first modern-era flights were credited to the Montgolfier brothers of Paris (1783) and balloon flight was subsequently associated with French schemes of progress and conquest during the Revolution, Directory, and Empire.
The eleven-year-old Mary Godwin produced a prose sketch (now lost) of a popular comic song, "Mounseer Nongtongpaw;" an imitation of Dibdin perhaps based on this sketch tells of an English tourist impressed with a "vast balloon" in Paris. The young Percy Bysshe Shelley was no doubt responding to these same associations of balloons with revolutionary (and French) ideas when he sent up incendiary political poems attached to balloons, as commemorated in his sonnet, "To A Balloon, Laden With Knowledge."