I have sketched the faces of the Tower Hill springhouse to show sizes of openings and overall dimensions. The first is the Street View shown below. This side of the springhouse faces west.
The north side of the springhouse has no windows or doors but the southern side has a single door as shown below:
The frame is 2 feet in from the eastern side of the springhouse and it is 42″ wide which includes the frame.
The east face has a window and an entry to the second floor.