Whenever it is necessary and expedient to lay out a new militia district, to change the lines of old districts, or to consolidate or abolish old districts, the judge of the probate court may, at any time, appoint three commissioners who are citizens of the district or districts from which it is proposed to make the new district or to change the lines thereof, whose duty it shall be to lay out and define the lines and to report the same to the judge of the probate court. The commissioners shall have authority to engage the services of a competent surveyor to assist them in their duties. The surveyor shall be paid for his services, out of the county treasury, the same compensation county surveyors are paid for similar services rendered to a citizen. If the judge of the probate court approves the report of the commissioners, he shall have all proceedings in the matter entered on his minutes, after which the district laid out or the line changed or defined shall be known and regarded accordingly.