Introduced in 1866. There are three marks of this gun, similar to the 7-inch patterns. The only way in which the 8-inch can be distinguished from the 7-inch without measuring the diameter of the bore is by the fact of its having four grooves in place of three.
9-inch R. M. L. 12 Tons.
Introduced in 1865. There are five marks of this gun, the first one being of the old Armstrong construction, and the others of the Woolwich developments. The distinctive mark of this calibre is the grooving, there being six grooves.
10-inch R. M. L. 18 Tons.
Introduced in 1868. There are two patterns of this gun, both of the Woolwich design. The distinguishing marks are the nine grooves.
11-inch R. M. L. 25 Tons.
Introduced in 1867. There are two patterns of this calibre, both Woolwich. But few of them are used in the navy. This calibre cannot be distinguished from the 12-inch, except by measurement.
12-inch R. M. L. 25 Tons and 35 Tons.
The 25-ton gun was introduced in 1864. There are two patterns, the first built on the old Armstrong pattern, there being but four in service. The second mark is Woolwich. The 35-ton gun was introduced in 1871. There is but one mark of this gun corresponding to the Woolwich.
