Photographs show that each rib forms a separate segmental right archA equal in width to three stretcher bricksB (each nominally 9 inches long), and offset from each of its neighbours by the width of six header bricks (each nominally 4½ inches (115 mm) wide), thus providing as a whole for a skew angle of approximately 45°.C This method of construction was first proposed by British-born American architect Benjamin Henry Latrobe in 1802 and later championed by French civil engineer A. Boucher, and has the advantage of being one of the simpler ways of building a skew arch, but set against that it has received considerable criticism for being "weak, ugly and wasteful of materials".