Ever since the first balloon ascent by the Montgolfier Brothers in 1783, it had been realised that for balloons to be really useful, they had to be navigable. Patrick Alexander applied his mind to this problem of airship propulsion. In 1893 and 1894 he filed a number of patents. His ideas included reciprocating oars and an adjustable-pitch propeller that resembled a pair of fans. One patent includes a means of heating the gas in the balloon envelope by using piped steam, the steam pipe also served to support the balloon in the shape of a parachute in the event of the balloon being burst or punctured. None of Patrick’s ideas ever came to anything; but throughout his life, he never lost faith in the practicality of airships.