The Brennan Torpedo, a propeller-driven dirigible torpedo, was invented by Irish-born Louis Philip Brennan (1852-1932) who arrived in Melbourne in 1861. Brennan attended Eade's Technical College in Collingwood, and was apprenticed to engineer A.K. Smith. Brennan had been associated with printer William Calvert in designs for a number of inventive devices, including an incubator and safety window catch, and jointly registered patents for an improved weighing machine in 1872. Brennan also developed a billiard marker adopted by manufacturers Alcock & Co. In 1874, with advice from William Charles Kernot, lecturer and later professor of engineering at the University of Melbourne, Brennan developed the 'fish torpedo', and in 1875 and 1876 Calvert and Brennan registered patents for improvements in machinery for propelling and guiding vessels through air and water. A patent for the torpedo was sealed in London in 1878, and with a grant of £700 from the Victorian Government and commercial backing from Melbourne businessmen John Temperley and Charles and Edwin Millar, the Brennan Torpedo Co. was formed. After tests in Hobsons Bay on 21 March 1879, Brennan further developed the weapon in Britain after 1880 where it was purchased from the company in 1887 by the British Government for £110 000. It remained at the forefront of coastal defence for two decades, and though the standard harbour defence at sites in Dover, Portsmouth, Gibraltar and Singapore, was never used in anger. Dual counter-rotating propellers were operated by wires attached to winding engines on shore, the trajectory guided by altering the speed at which the separate wires were extended. Brennan led production of the torpedo at Gillingham, and an example of the torpedo is on show in the Royal Engineers Museum at Chatham, Kent. A number of launch installations survive including at Cliffe Fort, Kent, built around 1885 to defend invasion of London via the Thames estuary.