This historical marker (p11752) reads:

These wheels used by the Confederacy to grind gunpowder at Augusta, Ga in 1863-1864 were made in Woolwich, England and were shipped on the blockade runner “Spray,” via Mobile. After the war Gen. Miles purchased them for use at Sycamore Powder Mills, Cheatham County. They were exhibited at the Tennessee Centennial Exposition in 1897.