In 1861 the company was experimenting with a Bessemer converter and in 1864 it was the first to adopt
the Bessemer process. From 1871 the company embarked upon a major investment programme to build
six Bessemer converters and two furnaces. The complex had just been completed in 1873. When the
mission visited the plant, the seventon converters were already in operation. The site covered a surface of
192 acres and included two coal mines, coke furnaces, an ironworks, a steelworks, a forging plant and
locomotive assembly and boiler manufacturing plant. The finished and half-finished products were moved
by cranes that hung from the ceiling, and over railways that ran criss-cross through the premises. The
company also made pig iron and steel cannon, but this was not a major section of its activities. It was at
one time the biggest steel mill on the continent. It had been visited by the Satsuma mission of 186553 and
the Tokugawa mission of 1865.