- Oct 1 1st Hawaiian stamps issued
- Oct 2 The pasilalinic-sympathetic compass(a contraption built to test the pseudo-scientific hypothesis that snails create a permanent telepathic link when they mate) is demonstrated but proves to be a fake.
- Oct 24 William Lassell discovers Ariel & Umbriel, satellites of Uranus
- Oct 30 Alfred de Musset's "Bettine" premieres in Paris