(1) Whenever any youthful offender is sentenced to transportation or imprisonment, and is, in the judgment of the Court by Co which he is sentenced, a proper person to be an inmate of a Reformatory School, the Court may, subject to any rules made by the State Government, direct that, instead of undergoing his sentence, he shall be sent to such a school, and be there detained for a period which shall be not less than 1[ three or more than seven years.