leave to sit - Permission for a committee to meet during the proceedings of the parent chamber. Under Senate Rule XXVI committees are forbidden to meet after the first two hours of the Senate's daily session, and in no case after 2 p.m. while the Senate is in session, without special permission from the majority and minority leaders.
Congressional Sessions lists all Congresses and corresponding years - from 1789, when the 1st Congress met, through the current Congress.
You can access legislative information, by bill number or key words, from the THOMAS Web site. Information from the present back to the 93rd Congress (1973) is available on THOMAS.
For information on the Senate, Congress, the legislative process and the federal government, the Virtual Reference Desk is a good place to begin.