Section 34. Said trustees shall have the management and control of the state library and of the moneys appropriated therefor. They may sell or otherwise dispose of such books belonging to the library as they consider unsuitable for its purposes, and they may deposit any duplicate volumes for safe keeping and use in any town, city or college library in the commonwealth, upon such terms and conditions as they shall prescribe. They may make and enforce rules for the use of the library, and shall see that its rooms are properly prepared for the accommodation of persons permitted to use them.