Manufacture of the Armstrong Gun at Woolwich Arsenal: finish-turning a 100-pounder, 1862. The gun, being now completely built up, is carried to a lathe for the purpose of being finish-turned, as is shown in our Illustration...This is performed in a portion of a lofty and extensive building, which we were told was formerly used as a foundry for the casting of the old pattern-guns, but has been transformed into two or three large shops, in which are powerful turning-lathes and other machines used in connection with the heavier class of guns. The workman in the Engraving is seen applying a gauge to the part of the gun at which the tool is cutting. This gauging is in order to ascertain that neither more nor less is being turned off than is required, as it is essential that each gun should be the duplicate, both in external and internal dimensions, of one which is retained in the department, and sealed, as a pattern to guide the manufacture of other guns of the same nature. From "Illustrated London News", 1862.