Upon the establishment of a museum under this act the board of county commissioners shall appoint a museum board of six (6) members for such museum. Two of the original members of such museum board shall serve for a one (1) year term from appointment, two (2) of the original members of such museum board shall serve for a two (2) year term from appointment, and the remaining two (2) members shall serve for a three (3) year term from appointment. As terms expire, all succeeding terms of members shall be for three (3) year terms. In addition to the appointed members of the board, the chairman of the board of county commissioners shall be ex officio a member of the museum board with the same powers as appointed members. Vacancies created during the term of any board member shall be filled by appointment for the unexpired term. Members of museum boards shall receive no compensation for their services as such but shall be allowed their actual and necessary expenses in attending meetings and in carrying out their duties as members.