The township clerk, under the direction of the trustees, shall be the custodian of the building, and the use thereof may be permitted by the township trustees to citizens of the township for any lawful purpose; and, for the purposes of this chapter, the township clerk is hereby clothed with all the powers and duties of a constable of the township, to maintain order within and about the premises, protect the property, and enforce orders of the township trustees with respect thereto. In case of joint ownership by the township and city, the duties herein enumerated shall devolve jointly upon the township trustees and the city authorities or they may purchase a building already built with the same limitations as in said section 360.4. A copy of this section shall be at all times kept posted in a conspicuous place in said hall.