So iron and brass parts came to replace wood and leather parts.
In 1728, J. Paine got a patent for rolling iron instead of
hammering it. The iron bars, being heated in a long hot arch or
cavern passed between two large metal rollers, which had certain
notches or furrows on their surfaces.
Around 1740, clockmaker and Quaker Benjamin Huntsman was struck
with the difficulty of finding finely tempered steel for the
springs of his watches and pendulums of his clocks. He
experimented for years to find a homogeneous and flawless metal,
and finally invented cast steel, which was much harder than
ordinary steel. He did this by remelting refined high quality
wrought iron bars at very high temperatures in sealed fireclay
crucibles, together with small quantities of charcoal and ground
glass as reagents. This distributed the carbon evenly in the
metal, which hammering could not do. He approached the Sheffield
cutlers, who finally agreed to try his cast steel for fear of
losing their business to some other manufacturers who were
approaching Huntsman. Since Huntsman had no patent, he worked at
night and employed only men who would keep his secret. His steel
was made at night. His factory became prosperous about 1770 and
the excellence of his steel manufacture was never equalled. Steel
and wrought iron was scarce and expensive.
Around 1748, iron founder Samuel Walker, discovered Huntsman's
secret by appearing at Huntsman's factory disguised as a shivering
tramp who asked to warm himself by the furnace fire.
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