This is an 1880 map of Eastham. Note that the railroad runs through Eastham and the pond to east of Great Pond is called Long Pond.
It can be purchased at Historic Map Works, Abe Books, or Maps of Antiquity.
This is a map from 1910. The pond to the east of Great Pond is now labled Depot Pond. This map can be purchased at Historic Map Works, Old Map Company, Etsy. or Old Maps.