Hugh Dorian was born in poverty in rural Donegal in 1834. He survived Ireland's Great Famine, only to squander uncommon opportunities for self-advancement. Having lost his job and clashed with priests and policemen, he moved to the city of Derry but never slipped the shadow of trouble. Three of his children died from disease and his wife fell drunk into the River Foyle and drowned. Dorian declined into alcohol-numbed poverty and died in an overcrowded slum in 1914.

A unique document survived the tragedy of Dorian's life. In 1890 he completed a "true historical narrative" of the social and...