opposite 54 Linden Street, Reading MA 01867;52 Sanborn Street, Reading MA 01867;"A BENCHMARK is a permanent monument, usually a brass plate, that is installed at a known elevation, and it is used by surveyors and engineers when bridges, roads, and other structures are being built. This practice was started in 1893 by the U.S. Coast and Geodetic Survey. (U.S.C.& G.S.) In 1930, the Massachusetts Departmnet of Public Works became interested in the project and started to do its own surveying. Their measurements were then sent to Washington for verification and adjustment by the U.S.C.& G. S. Many Benchmarks can be found in Reading: on the roof of the Community Center, on the cupola of the Old South Church, and there is even one in the Ipswich River at the Reading-North Reading town line." From the album containing the photograph.
Benchmarks -- Massachusetts -- Reading -- Pictorial works
Reading (Mass.) -- History -- Pictorial works.
"Reading benchmarks," in NOBLE Digital Heritage, Item #13903, http://heritage.noblenet.org/items/show/13903 (accessed January 18, 2017).