If the managers are reasonably sure that the person is entitled to vote, they shall then deliver a ballot to such person, and thereupon the voter shall immediately go to the booth and mark his ballot preparatory to depositing it in the ballot box. After the voter has marked his ballot, he shall fold it so as to leave the stub remaining attached thereto visible in such position that it can be detached without unfolding. When the ballot is returned, one of the managers shall detach and retain the stub, and the voter shall then deposit his folded ballot in the box.