By Wednesday 28th December 1814, Mary Wollstonecraft Godwin was back in London, after returning from her elopement to the continent with Percy Shelley in September. Aged 17, she was 5 months pregnant and, at that point, estranged from her father, and lived with Shelley, as yet unmarried.
Her journals for the 28th December record an outing that night that seems likely to have later have played a part in influencing her first novel, which she would begin 18 months later:
[Shelley & I]—go to Garnerin's lecture—on Electricity—the gasses—& the Phantasmagoria'Phantasmagoria' was the name given to an exhibition of optical illusions via a magic lantern, a relatively new but very popular form of entertainment. It had also already come to mean a series of real or imaginary images experienced in a dream, or fever-like state. It was also the name of a French collection of German ghost stories, translated by Jean-Baptiste Benoît Eyriès, which Byron would read to Mary, Shelley and others 18 months later at the villa Diodati.
Garnerin was André-Jacques Garnerin, a pioneering French balloonist & parachutist, with a now lesser-know sideline in this kind of show. A front-page advert in the classified section of The Times of the preceding day announced his show:
THEATRE of GRAND PHILOSOPHICAL RECREATIONS.—The Professor GARNERIN has the honour to inform the Nobility and Gentry, that in consequence of his engagements at Covent-garden, his Theatre will be open this week, Wednesday, Thursday, and Saturday, and he hopes to merit the approbation of his numerous visitors, by his new experiments on the Electricity, Gas, Aerostation, Fantasmagoria, &c. The performance begins at 7 o'clock. Spring-gardens room.