Made by J Whitworth & Co, Manchester. Sir Joseph Whitworth (1803-1887), was an English mechanical engineer who pioneered precision measurement. He created a small workshop to produce hand tools which expanded to make machine tools and engines, including steam engines. Whitworth's factory also produced small arms and later, big guns, and improved the quality of steel by subjecting the molten metal to pressure during its solidification, later known as 'Whitworth steel'.
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