No person shall be eligible for or shall continue to hold the office of commissioner, deputy commissioner, secretary to the department, if any there be, or head of a division who is engaged in the business of lumbering in any forest preserve county or who is engaged in any business in the prosecution of which hydraulic power is used or in which water is distributed or sold under any public franchise or who is an officer or holder of stocks or bonds of any corporation engaged in such business within the state.