On the filing of such application, the judge of probate must issue to the sheriff a writ, setting forth the substantial averments contained in the application, the name of the applicant and the place where it is proposed to erect the dam and commanding the sheriff to summon seven disinterested freeholders of the county to meet at the place where the dam is to be erected, on a day to be specified in the writ, not less than 15 nor more than 30 days after the filing of the application, and then and there to inquire touching the matter contained therein.