The said joint commission is hereby authorized and empowered to appoint a treasurer, who may or may not be a member of said joint commission, a secretary, and such engineering, architectural, and construction experts, inspectors, and other employés, as in the opinion of the joint commission may be necessary, all of whom shall do such work as the joint commission shall direct. The joint commission shall fix the compensation of the respective persons so appointed.
36 P.S. § 3392