After her most interesting talk, Diana was thanked by Secretary, Mike Burgess MM0MLB. ......................................................................................................................................This shortened version of Diana Maxwell's talk is reproduced with grateful thanks to her. 
...................................................................................................................................... The photographs shown by Diana Maxwell in her talk are copyrighted by the National Maritime Museum and therefore cannot be reproduced here. The text of her talk follows: Views and location of the Hawkcraig station near Aberdour, Fife during WWI Hawkcraig was a busy establishment in WWI but almost nothing remains of it today. Views of the station looking inland today and in WWI. Comparative views looking out into the Firth of Forth. Captain Cyril Ryan, who was in charge of Hawkcraig, standing outside his local cottage. Our speaker, Diana Maxwell, now lives in what was Capt. Ryan's cottage but did not discover this until she was well into researching the project. Imagine her pleasure! There was a launching ramp for seaplanes at Hawkcraig for submarine spotting. The hydrophone, an underwater microphone, was the key component in the technology developed at Hawkcraig for detecting submarines in the very early days of electrical science. It was deployed in various ways - on submarines, drifters and on the sea floor. HMS Tarlair was the first drifter used in the hydrophone trials in 1915. Its name was adopted by the Admiralty for the Hawkcraig station A hydrophone mounted on a tripod base for positioning on the sea floor. HMS Tarlair was the Navy’s main hydrophone research and training base throughout the First World War. 1,090 officers and 2,731 ratings attended courses there or were trained off site by travelling teams of instructors from Hawkcraig.
By the end of the war 650 ratings and 120 officers manning 31 hydrophone stations at home and abroad, including ships, were attached to HMS Tarlair.
Training class at Hawkcraig.
A shore hydrophone station with the operators listening intently on headphones to the sounds coming from the hydrophones. In May 1916 Professor William Bragg, and later Professor McGregor-Morris from East London College, arrived at Hawkcraig to work on the bidirectional hydrophones and went on to produce a unidirectional hydrophone.Captain Lawrence Bragg, Professor Bragg’s son, visited Aberdour in 1916. It was shortly before this that the Braggs received the Nobel Prize (Physics) for their work on X-rays and crystal structure.
Sir Hamilton Harty, conductor of the Hallé Orchestra, was one of many top musicians who brought their gift of 'perfect pitch' to the identification of the characteristic sounds and frequencies of submarines picked up by the hydrophones. (If only frequency meters and oscilloscopes had been available in those days)! A special viewing platform was built at Hawkcraig for the visit of King George V in 1918. The components of a drifter hydrophone set manufactured at HMS Tarlair. HMS Tarlair staff fitted ship-borne hydrophones to submarines, and special sets were issued to the 1,500 drifters and motor launches in the Auxiliary patrol. These vessels formed the backbone of the Navy’s anti-submarine force.The training was effective, as on 25th October 1918 the telephonist Geoffrey Clough, on watch in HM submarine G2, picked up underwater transmissions made by the German submarine U78. By the strength of the acoustic signal he enabled the G2 to be guided towards the German boat, which was torpedoed as she lay on the surface. This was the first recorded occasion in which a British submarine’s hydrophones played a major role in the sinking of another submarine.
Lt. Black with torpedo tube used in experiments on remote control of torpedoes. The Seagull Decoy was a device that attracted seagulls to its periscope when food was discharged, in the hope that they would do the same thing when they spotted a real submarine periscope and draw the attention of the waiting gun crews. The scientists proved that the velocity of sound in the sea was approximately four and half times that in air. They detected the noise of a large ship’s propeller at 12 miles. They discovered ways of obtaining sound direction underwater.They eventually produced a “fish” containing the remotely controlled unidirectional hydrophone.
Ryan continued to develop the hydrophone and especially a fish type of towed hydrophone (the Eel), which was accepted by the Admiralty in October 1917. The Porpoise was Ryan’s most advanced hydrophone, which came into production in September 1918.
Hydrophone mines were another anti-submarine device designed by Ryan. A magnetophone was placed in a mine in series with detonators and a firing circuit. The magnetophone was activated by sound waves, which caused variations in the magnetic field. This produced a small current to be sent out along the cable to the receivers at the controlling station. The range of audibility was 200 yards.Magnetophone mine
The first shore controlled minefields making use of the magnetophone and hydrophones were laid in mid-1916. They were known to have accounted for the destruction of two U-boats and possibly two others. The last U-boat to be sunk in the First World War was UB116. She was destroyed on 28th October 1918 when passing over the magnetophone minefield at Scapa Flow.
The Photophone.Professor Alexander O Rankine from University College London introduced the photophone (a method of communicating across long distance by the modulation of a beam of light by speech) to the programme of scientific investigations. This involved fitting up a transmitting mirror at Hawkcraig and a receiving mirror on Inchcolm Island, one and a half miles away.The photophone was designed for use as a short-range communication device between ships of a fleet, but was apparently never used for this purpose.
It was, however, very frustrating to the operators at both ends when the beam was not accurately directed and there was no alternative means of To simplify the theory of the photophone: It operated a speech-modulated beam of light, transmitted by a large convex lens (mirror). The lens on a small concave mirror attached to a gramophone sound box or telephone earpiece focused the light from a point light source. The light diverged and passed through a similar lens, which projected the beam to a distant receiver. There, two similar grids were mounted, one in front of each lens. An image of the first grid was superimposed on the second by reflection in the small concave mirror. This caused the latter to oscillate under the vibrations of speech, as the dark spaces of the image grid moved over the openings of the second grid producing fluctuations of intensity of the light beam. This was collected at the receiving end by a mirror or lens and focused on a photoelectric selenium cell in a circuit with a battery and a telephone earpiece. The resistance changes of the selenium resulted in the reproduction of the original sound in the receiving telephone (without an amplifier!). When the light beam from Hawkcraig was picked up at Inchcolm the speech was easily audible and of good quality. communication between the two points.
Professor Bragg managed to persuade Captain Ryan to lay a spare length of hydrophone cable to be used as a telephone line between the two photophone stations. This enabled the two points to be in continuous audible contact, which was a marked improvement. Unfortunately, only two weeks later when Professor Bragg was attending a meeting in London, Captain Ryan ordered one of his officers to take the cable away!!The photophone method of modulating a beam of light by speech was, however, used after the war by Rankine for recording speech on film, which was used in the development of the first “talking” films which were then in their infancy.
By the end of 1918 it was possible to look back on very significant progress in the field of underwater detection. However, the problem of defining the exact depth and position of the submarine remained, which was solved with the coming development of the Asdic or Sonar, as it is now known.
The final tally of World War I proved that four U-boats sank as a direct result of hydrophone contacts (UC49, U78, UB107 and UB115). The large number of anti-submarine vessels fitted with detection devices also made a very significant contribution to the harassment of the U-boats and the development of anti-submarine tactics. In 1918 there were 54 sightings of U-boats in which hydrophones played a part.
In his memoir “The Crisis of the Naval War” Admiral of the Fleet Viscount Jellicoe wrote that, “They were also greatly indebted to Capt. Ryan R.N., for the exceedingly valuable work carried out by him at the experimental establishment at Hawkcraig. Many brilliant ideas were due to Captain Ryan’s clever brain.”
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