'Sorry to destroy romance by fixing him with a local habitation,' says Mortimer. 'But he comes from the place, the name of which escapes me, but will suggest itself to everybody else here, where they make the wine.'
Eugene suggests 'Day and Martin's.'
'No, not that place,' returns the unmoved Mortimer, 'that's where they make the Port. My man comes from the country where they make the Cape Wine.'Now this slightly complicated joke that will probably not gain in hilarity from being explained. But here I go anyway. In the nineteenth-century, boot blacking was sold either as a paste, or else in liquid form. The main manufacture of this latter kind were Day and Martin [‘To give some idea of the extent of the operations still carried on at "Day and Martin's," it may be stated, that on the average 150 casks, containing a quantity of blacking equal to 900 dozen pint bottles, are sent out per day. ‘Black Manufacturers’, Exhibition of the Works of Industry of All Nations (1851), 631]. Now, the bottles in which this blacking was shipped were widely reused to serve wine that had been bought in a cask or butt [‘wine is wine, whether in a hogshead, a flask or one of Day and Martin’s blacking bottles’ Blackwood’s Edinburgh Magazine 10 (1821), 79]. Hence Eugene’s joke. Mortimer’s riposte invokes the facetious habit of describing bad port wine as ‘boot blacking’ (For instance: ‘we drank the health of our entertainer in a glass of most execrable port-wine, which my husband stigmatized as "Day and Martin's blacking, ink," &c.’ Anne Mathews, Memoirs of Charles Mathews, Comedian (1839), 3:134). So there you have it.