As soon as the means in its hands will permit, without incurring indebtedness, said board shall proceed to obtain a suitable location, and lease or erect such buildings, and procure such furniture, apparatus, library, and implements, as may be necessary for the successful operation of said school, and to appoint a principal, and such other teachers and assistants as the board may deem expedient, with salaries, to be paid from time to time, as it may agree, and to regulate their duties; but no agreement shall be valid whereby such board shall be prevented from discharging any one in their employ upon 2 months previous notice.