Special meetings of the Board may be called at any time by the Chairperson and shall be called by the Clerk upon written request of a majority of the members of the Board. Each supervisor shall be given at least 24-hours' notice of any special meeting by telephone, or by written notice delivered personally, or by regular mail. Notice by mail is effective upon deposit in the mail at least 72 hours before the special meeting. Supervisors waive the notice requirements if they attend the special meeting, unless attendance is for the sole purpose of protesting the holding of the meeting. No action may be taken at a special meeting which is not warned specifically in the notice.