(a) subject to such rules and the statutory powers of the commissioner, take care of the general interest of the institution and see that its objective is carried into effect;
(b) maintain an effective inspection of the institution, for which purpose the board, or a majority of its members, shall visit and inspect the institution at least once every three months;
(c) keep in a book provided for that purpose, a fair and full record of its activities, which shall be open at all times to the inspection and examination of the governor or of any person appointed by the governor or by either house of the legislature, or to the commissioner or his authorized representatives;
(d) enter in a book, kept at the institution for that purpose, the date of each visit of each visitor;
(e) investigate, hear and ascertain the truth of all charges made against the director or other officer or employee of the institution, issue subpoenas, take and hear testimony in respect to such charges and make its recommendations thereon to the authority having the power to discharge or remove. A witness attending before such board shall be entitled to the same fees as a witness attending before a court of record or a judge thereof, which shall be paid as other institutional charges.