§ 100. Appointment and salary of county superintendent. The board of supervisors of any county may appoint a county superintendent, determine the amount of the bond which he shall give, fix his salary, and provide for the payment of all the necessary expenses incurred while in the performance of his duties, which salary and expenses shall be a charge against the county road fund, and may remove such county superintendent for malfeasance or misfeasance in office, upon written charges, after an opportunity to be heard, not less than five days after the service upon such superintendent of a copy of such charges. The term of office of each superintendent or county engineer appointed by any other law to perform the duties of county superintendent shall be four years unless sooner removed by the board of supervisors as above provided.