user: Question: Which Incumbent has a District of Massachusetts 8?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Massachusetts 1', 'Thomas D. Eliot', 'Republican', 1858.0, 'Re-elected']
SQL:

assistant: SELECT "Incumbent" FROM "Table" WHERE "District" = 'Massachusetts 8';