The National Geographic Magazine, later shortened to National Geographic, is the official journal of the National Geographic Society. It published its first issue in 1888, just nine months after the Society itself was founded. It is immediately identifiable by the characteristic yellow frame that surrounds its front cover.

An account of the evolution of Japanese defensive architecture and engineering, from early earthworks through to wooden and earth castles and, finally, the emergence of the stone towers that are so characteristic of the samurai.

He also plots the adaptation of Japanese castles to accommodate the introduction of firearms.