_Staff Officers_ of all ranks wear the Corps device or insignia indicating the particular corps to which they belong (as described on page 121) in place of the silver foul anchor above described and the same rank insignia for the different ranks as described for Line Officers. Thus, a Medical Director with the rank of Captain wears the silver spread eagle indicating the rank and the Medical Corps device of the silver acorn upon the gold leaf indicating the Medical Corps; a Pay Director with the rank of Captain wears the silver spread eagle indicating the rank and the silver oak sprig of three leaves and three acorns indicating the Pay Corps; a Chaplain with the rank of Commander wears the silver leaf indicating the rank and the silver Latin cross indicating his corps; a Professor of Mathematics with the rank of Commander wears the silver leaf indicating the rank and the silver oak leaf and acorn indicating the corps; a Naval Constructor with the rank of Commander wears the silver leaf indicating the rank and the silver two live-oak leaves and acorn indicating the Construction Corps; a Civil Engineer with the rank of Commander wears the silver leaf indicating the rank and the silver crossed live-oak leaves indicating the Corps of Civil Engineers; and a Dental Surgeon with the rank of Lieutenant wears the two silver bars indicating the rank and the gold oak leaf and silver acorns indicating the Dental Corps. The insignia showing the corps of the Chief Boatswain, Chief Gunner, Chief Machinist, Chief Carpenter, Chief Sailmaker, Chief Pharmacist and Chief Pay Clerk consist of devices worn on each side of the collar of the frock coat just above the V notch in the lapel, as follows: Chief Boatswain—two foul anchors crossed, embroidered in silver, surcharged at the center by a gold five-pointed star. Chief Gunner—a flaming spherical shell, embroidered in silver, surcharged at the center by a gold five-pointed star. Chief Machinist—a three-bladed propeller embroidered in silver, surcharged at the center by a gold five-pointed star. Chief Carpenter—a carpenter’s square, embroidered in silver with the point down. Chief Sailmaker—a diamond embroidered in silver. Chief Pharmacist—a caduceus, embroidered in silver. Chief Pay Clerk—an oak sprig of three leaves and three acorns, embroidered in silver. The Corps of Warrant Officers is also shown by corps devices worn on each side of the collar of the frock coat just above the V notch in the lapel, as follows: Boatswain—two foul anchors crossed, embroidered in gold, surcharged at the center by a silver five-pointed star. Gunner—a flaming spherical shell, embroidered in gold, surcharged at the center by a silver five-pointed star. Machinist—a three-bladed propeller, embroidered in gold, surcharged at the center by a silver five-pointed star. Carpenter—a carpenter’s square embroidered in gold with the point down.