In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Watercombe like this:
WATERCOMBE, an extra-parochial tract in Weymouth district, Dorset; 5½ miles SE of Dorchester. Pop., 37. Houses, 7.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Watercombe has changed, please see our redistricted information for the modern district of West Dorset. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Watercombe and units named after it.
GB Historical GIS / University of Portsmouth, History of Watercombe in West Dorset | Map and description, A Vision of Britain through Time.
Date accessed: 28th July 2016
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Watercombe".