Subject to the provisions of the Merit System, the State Geologist may appoint, with the approval of the Governor, such assistants, including a competent chemist, for such periods and with such compensation as he may deem necessary to the best interests of the survey; provided, that said assistants shall devote their entire time to the work of the survey, and no part of the funds available to the survey shall be expended for the salary or compensation in whole or in part of any member of the teaching staff or other employee of the University of Alabama, provided that not more than one of the present employees doing joint service may be retained, the object of this provision being to secure the services of full-time employees and to preclude the payment of salaries or other compensation of teachers or other employees of the university, thereby guaranteeing an entire separation of the work of the survey from that of the university.