The first sprinkler system. A signed and dated affidavit to patent a 'mode of construction or arrangement for any building, so as to afford security against fire' by Sir William Congreve (1772-1828), comptroller of the royal laboratory at Woolwich from 1814 until his death in 1828. A brilliant military technologist, Congreve had earlier won renown for the development of a rocket system based on Mughal principles which had been used with effect against the British during the Anglo-Mysore Wars.

The invention followed a devastating fire that destroyed the old Theatre Royal at Covent Garden in September 1808. Congreve's solution was in effect a modern sprinkler system. A series of perforated pipes were to be connected by fusible links to an outside control valve, in the event of a fire, water could be poured through the system to be evenly dispersed across the building. In 1812 the design was installed at the Drury Lane theatre after it too had succumbed to fire in February 1809.

Single leaf folded in two; signed 'William Congreve', old catalogue description tipped to upper margin recto, MS note tipped to verso, blind stamped 'Two Shillings Six Pence'; minor soling to verso, small cosed tear not affecting text, right hand edge rubbed.