Nice Gilt Brass Non Dug Union Civil War Engineer Coat Button

Non dug Union Civil War, low convex 2-piece, Engineer coat button. It has a depressed, c.1860, SCHUYLER HARTLEY & GRAHAM * N. Y. * backmark. The front has a spread wing eagle, holding a banner in its beak, above the water, a fort, and the sun. The design on the front is not the one usually seen with this backmark. Perhaps this is a rare variant? The shank is slightly bent and the button measures 23 mm's in diameter. $165