Such boards shall register and conduct the registration of the electors who shall apply for registration in their respective counties as herein required. Their office shall be at the county seat, and they shall keep a record of all their official acts and proceedings. Provided, that nothing herein shall be construed as prohibiting the boards of registration from taking their registration books across adjoining county lines to register qualified electors of their respective county whose regular place of employment is in an adjoining county or who are otherwise unable to get to the county seat during office hours to register. One member of the board shall constitute a quorum for the purpose of registering or refusing to register applications for registration.