Erastus and Horatio Bigelow ended their involvement in the management of the Lancaster Mills Company in Clinton (producers of gingham cloth) in 1849. The new manager, Franklin Forbes, oversaw the erection of new buildings, including Mill No. 7 (Carding Mill, also labeled in 1929 as Ring Spinning), which was built between 1857 and 1870. It has a six-story tower added c. 1879-1898. Mill No. 7 is connected to Mill No. 1. The mills closed in 1931. For several decades the buildings were owned by Colonial Press and then were used by other companies. Recently, they have been renovated as condominiums, the Lofts at Lancaster Mills.

Mill No. 7 is also connected to the later Mill No. 3 (see image below), built in 1910. Designed by Knight C. Richmond, an engineer from Providence, Rhode Island, Mill No. 7 follows a vertical design, typical of its era, with different functions on separate floors. The building was known as the Amory Mill due to the Amory family’s long association with the company. James S. Amory had been treasurer from 1847 into the early 1880s, by which time Harcourt Amory was listed as clerk, director and treasurer of the Lancaster Mills.