Dating 20th century
The mouldings on stonework on the other hand remain a matter for comparative analysis alone. In London for example, a plain 18th century terrace house can usually be dated to within five or ten years simply by looking at it with an informed eye.
Furthermore, there are rich documentary sources from which, in much of London north of the river at least, it is possible to date a house even more accurately.
At one time this was regarded as almost unnecessary, but the revolution brought about by Howard Colvin's has changed the nature of post medieval architectural history.
Historians always like to confirm a date suggested by the physical evidence against any available documentary sources.
To determine age, consider the form and function, tool marks, construction techniques, and materials used in the furniture. Pit saws, used from roughly the 1600s to 1750, left irregular, slanted, deep rough marks.