The probation officers, and assistant probation officers, and deputy probation officers in all counties of the state shall be allowed such necessary incidental expenses as may be authorized by the judge of the juvenile court, and the same shall be a charge upon the county in which the court appointing them has jurisdiction, and the expenses shall be paid out of the county treasury upon a written order of the judge of the juvenile court of said county directing the county auditor to draw his or her warrant upon the county treasurer for the specified amount of such expenses.