First class Gunner, Gun Company, Coast Artillery—A projectile, point up, with a bar below it. Second class Gunner, Gun Company, Coast Artillery—A projectile, point up. First class Gunner, Mine Company, Coast Artillery—A mine case with a bar below it. Second class Gunner, Mine Company, Coast Artillery—A mine case. Gun Commander, Coast Artillery—Two crossed cannon with a bar below, enclosed in a circle. Gun Pointer, Coast Artillery—Two crossed cannon enclosed in a circle. Observer and plotter, Coast Artillery—An equilateral triangle with a bar below it, enclosed in a circle. Observer, Second Class, Coast Artillery—An equilateral triangle enclosed in a circle. First Class Private, Signal Corps—The crossed flags and torch device of the Signal Corps. [Illustration: U. S. Army. Noncommissioned officers’ chevrons Ordnance Corps 1. Ordnance Sergeant 2. Sergeant of Ordnance Corps 3. Corporal of Ordnance Corps 4. First Class Private of Ordnance Corps] [Illustration: U. S. Army. Noncommissioned officers’ chevrons Medical Corps 1. Sergeant, First Class 2. Sergeant 3. Corporal 4. Lance Corporal] _Cap Insignia._—The insignia for the front of the caps of all enlisted men are circular disks one and one-half inches in diameter with a raised rim encircling the coat of arms of the United States, made of gilt metal for dress caps and of bronze metal for service caps. _Collar Insignia._—The corps, department or arm of the service of enlisted men of the U. S. Army is shown by insignia on the coat collars. _For blue dress and white coats_ these insignia, of gilt metal, worn on each side of the neck opening, consist of block letters and special devices in rear of the letters. The letters “U. S.” for Regular Army, “U. S. V.” for Volunteer Army, “U. S. R.” for Enlisted Reserve Corps, “U. S.” with “N. G.” superimposed for National Guard drafted into the Federal service and “U. S.” with “N. A.” superimposed for National Army. The special devices are: