It was he, moreover, who proposed the flash-light for lighthouses, as a means by which seamen might identify lighthouses. He proposed that a powerful light should be made by periodic flashes to correspond with the number of the lighthouse, and that every lighthouse along the coast should have a registered number, so that the number of flashes per minute should represent the lighthouse. Gurney was present at Sir W. Snow Harris's experiment on Somerset House terrace with wire for ships' lightning-conductors. Turning to Sir Anthony Carlisle, in reference to the magnetic needle which, as he observed, made starts on meeting the poles of a galvanic battery, he said with the inspiration of genius, "Here is an element which may, and I foresee will, be made the means of intelligible communication." Whilst engaged at the Surrey Institution he invented the oxyhydrogen blow-pipe. Before this was introduced the risk of accident was so great that recourse was seldom had to oxyhydrogen. Gurney applied his steam-jet to other purposes than propelling locomotives and exciting the ardour of furnaces in ironworks. By its means he extinguished the fire of a burning coal-mine at Astley, in Lancashire, and in 1849 another at Clackmannan, where the bed of coal had been burning for over thirty years. He also employed it for expelling noxious gases from sewers, and planned and superintended in 1849 the ventilation by this means of the pestilential sewer in Friar Street, London, which resisted all other efforts to cleanse it; and he suggested to the metropolitan commissioner of sewers that a steam-jet apparatus should be placed at the mouth of every sewer emptying into the great main sewer by the Thames river-side. He was employed on the lighting, heating, and ventilation of the old House of Commons, and he held the appointment of superintendent of these functions from 1854 to 1863. He had remarked that the flame of hydrogen gas caused vibrations that produced musical tones, and in 1823 wrote on "the analogy between chemical and musical combinations." He suggested "an improved finger-keyed musical instrument, in the use of which a performer is enabled to hold or prolong the notes, and to increase or modify the tone at pleasure." In 1825 and 1833 he proposed "certain improvements in musical instruments." He invented a stove, and saw and advocated the advantage of the employment of circulation of hot water for the heating of a building. He advocated the employment of concrete for foundations where there was no rock, and to show that it was possible to build a house upon the sand, he reared the castle at Bude upon concrete floated into the shifting sand above high-water mark. He again was the first to point out and insist on the necessity for there being two shafts to every colliery, so as to maintain a circulation of air.