Lassell, who was born at Bolton in Lancashire, was a brewer by profession who became interested in astronomy. He built an observatory for himself at Starfield near Liverpool and developed an interest in techniques for building very large reflectors, which he used himself. In 1844 he began building a 24-inch (61-cm) reflector with which – just 17 days after the discovery of Neptune in 1846 – he discovered Neptune's largest satellite, Triton. He also discovered Hyperion (a satellite of Saturn) and the crepe ring of Saturn independently of William Bond. In 1851 he discovered two satellites of Uranus – Ariel and Umbriel – from observations made in Malta (where the atmosphere was clearer than in industrial England). In Malta in 1861 he built a 48-inch (122-cm) reflector and observed and cataloged hundreds of new nebulae.