The original name of 150-acre Mirror Lake, at the southern base of Mt. Hosmer, was Oyster River Pond; the Oyster River rises in the lake and flows into the St. George River in Warren. The "History of Camden and Rockport, Maine," published in 1907, described Mirror Lake in the late 1800s as having “water of extraordinary purity.”  With the founding of the Camden & Rockland Water Company in the 1880s, it became the water supply for Camden and Rockport as well as most of Rockland and Thomaston. This photo along with 60,000 more is available online in the Penobscot Marine Museum's online database. PenobscotMarineMuseum.org.