The rents, profits, and annual income of all real and personal estate which may be vested in the said Board, together with all funds which may from time to time be derived from fees or payments made in respect of scholars or students attending the said High School shall be applied by them for the maintenance of the said High School, and the payment of all salaries and expenses connected therewith, and for prizes, exhibitions, and scholarships for the students therein: Provided that the said Board shall have power to set apart, if they shall see fit, out of the said rents, profits, and annual income, such part as they shall consider advisable, either as an addition to the capital fund, which shall then be invested in manner hereinafter mentioned, and dealt with as part of such capital fund, or as a reserve fund to meet extraordinary expenses, which shall be invested and dealt with in such manner as the said Board shall direct.