user: Question: What was the district Incumbent Julius Kahn was in that was smaller than 1906?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['California 1', 'William F. Englebright', 'Republican', 1906.0, 'Lost re-election Democratic gain']
SQL:

assistant: SELECT "District" FROM "Table" WHERE "First elected" < 1906.0 AND "Incumbent" = 'Julius Kahn';