In Cambridge, the grass around a large Victorian-style schoolhouse is neatly trimmed, although the building itself is boarded up and surrounded by a chain-link fence. But what might seem spooky and forgotten is a place that holds many beloved memories for generations of Cambridge children. The Dorchester County Board of Education bought the acre land in 1872 and built what was originally known as Academy School, but in 1902, workmen thawing frozen pipes accidentally caught th