Day, Thomas, 1748-89, English social reformer and author. He supported the American Revolution and the abolition of slavery and was interested in improving the lot of the small farmer. His moralistic History of Sandford and Merton (3 vol., 1783-89) contrasts the "natural" education of the virtuous Sandford with the conventional one of the objectionable Merton. In Lichfield he was a member of the literary group centering about Anna Seward.