Unusual brass adjustable chart light, American or English, circa 1920.  The lamp has a brass mounting bracket and has a locking pivot.  It has a 13 3/4 inch arm which has a second locking pivot which allows the arm to telescope 18 1/2 inches. At the end of the arm is a locking ball which allows the "L" shape lamp head to swivel in any direction.  The end of the lamp has a 6 1/4 inch diameter brass shade which is removable.  The lamp is mounted on a later rectangular mahogany board. (MI-517) 
Condition:  excellent.