The Boston Directory for 1870 has an entry for Francis Duffee & M. H. Hartnett, plumbers, 21 Hawley, and Hancock, n. Columbia, h. Stoughton, n. Pleasant, ward 16 [Dorchester] and for Michael H. Hartnett, Duffee & Hartnett, 21 Hawley, house Cottage, cor. Boston, ward 16.