The Secretary of the Navy may prescribe the amount to be credited to a midshipman, upon original admission to the Naval Academy, for the cost of his initial issue of clothing and equipment. That amount shall be deducted from his pay. If a midshipman is discharged before graduation while owing the United States for pay advanced for the purchase of required clothing and equipment, he shall turn in as much of his clothing and equipment of a distinctively military nature as is necessary to repay the amount advanced. If the value of the clothing and equipment turned in does not cover the amount owed, the indebtedness shall be canceled.