Complex sentence: After the discovery of iron stone locally, the principal ironworks were built by the British Iron Company in 1825; the works passed to the New British Iron Company in 1843 and to the Ebbw Vale Company in 1852, before closing in 1889.
Split into simpler sentences: After the discovery of iron stone locally, the principal ironworks were built by the British Iron Company in 1825. The works passed to the New British Iron Company in 1843 and to the Ebbw Vale Company in 1852, before closing in 1889.