"a half-cut novel, in the form of letters, by Madame de Souza"
Adelaide Filleul, Marquise de Souza
(1761-1836) was a French writer, reputed to be the illegimate daughter of Louis XV of France. Her Parisian salon attracted famous eighteenth century figures such as Talleyrand, to whom she reputedly bore a son. In 1789 Madame de Souza fled the French Revolution, settling in Surrey in England, where she supported herself by writing novels.
It was common for books to have pages that were left 'uncut'; the first reader of the volume would keep a paper knife handy to separate the pages as they read.