The several counties of this state bordering on the tide water of the Gulf of Mexico are authorized and empowered, in the discretion of the boards of supervisors of such counties or of any of them, to provide for the proper illumination of all such bridges and other parts of any of the public highways running in, through, or across said counties or any of them as, in the discretion of said boards of supervisors, may be deemed reasonable and necessary. Said boards of supervisors may and shall have authority to appropriate a reasonable and proper sum, to be paid out of the general county fund, for payment of the expenses of providing said system of illumination and the maintenance thereof.