Kevin Register is correct. It is for voting, but more precisely it is a "blind ballot box". A Steward would carry the box from its station to a table in the middle of the hall. Each voting member would then be lead through a procession (by the Steward and the Assistant Steward one for each side of the hall) to the voting table in a single file line. This prohibits anyone from seeing another person vote. The open portion of the box would contain both black and white marbles. If you were casting a yes vote you would move a white marble into the closed portion through the hole--black for a no vote. Once the vote was complete and everyone is seated the Steward would carry the ballot box the Master (or President) of the organization who would open the closed portion and look to see if the vote was passed (frequently a membership vote). Incidentally, more recent versions of this box have been reformated slightly and fully lined with a thick felt inside of the closed portion. This has enabled the substitution of black cubes for the black marbles allowing blind members to vote as well by dropping a black cube in rather than a white marble.

Or maybe its just a maraca.