Crown saw, yard No 1909, c 1804.

This rounding machine is part of the block-making machinery installed at Portsmouth between 1803 and 1805. French-born engineer Marc Isambard Brunel (1769-1849) revolutionised the manufacture of ships' pulley blocks for the Navy. Brunel's design enabled a series of machines to perform their operations without the need for skilled labour, apart from that needed to move the pieces and place them in the machines. Each Portsmouth machine carried out a single proces so that forty-five machines were needed to complete the parts for blocks for all sizes. English precision toolmaker Henry Maudslay (1771-1831) helped Brunel develop his block-making machinery.