ELECTRIFIED GIRDLE SAVES SHIPS

Southland Times, Issue 24106, 20 April 1940, Page 11

ELECTRIFIED GIRDLE SAVES SHIPS

Navy’s Secret Triumph Over Magnetic Mine

LONDON. GERMANY’S magnetic mine is beaten. It is now i-evealed that in 1938 Germany was busily constructing her “murder” mine—the magnetic mine—which has been laid in large numbers in the shallow waters round the British coasts, put overboard from submarines, and dropped with a parachute attachment (enclosed within the upper end of the mine) from raiding seaplanes.

What it took Germany two years to perfect, at unknown cost, has now been completely set at naught by British naval experts within three months of the laying of the first magnetic mine, generally believed to be the secret weapon mentioned by Herx- Hitler in his speech in Danzig on September 19.

Back in the third week in November the first magnetic mines were sown on the east coast of England, and within three days one of these new menaces was dropped “on our doormat.” A mine was found high and dry at low tide on the mud flats off Shoeburyness, east of Southend, on the northern side of the Thames Estuary.

Perilous Investigations

"YTOBODY has yet been announced as xi the prime mover in discovering and applying the remarkably simple equipment which demagnetises ships, makes them like wooden ships, and incapable of setting off the magnetic mines; but the award of the D.S.O. has been bestowed by the King on the man who, at the imminent risk of his life, dealt with the Shoeburyness mine and enabled the counter-measure to be embarked on. He was LieutenantCommander J. G. D. Ouvry, summoned from H.M.S. Vernon, the torpedo research school, with others, including Able Seaman Baldwin, who also was decorated for his work on that occasion, but who has since been killed during the investigation of another mine (nonmagnetic).

It was a lone and perilous job for Lieutenant-Commander Ouvry. In the moonlight, accompanied by Baldwin and other ratings, he trudged out over the soft mud flats and saw for the first time a magnetic mine. A local photographer was engaged to take flashlight pictures of the strange object as it lay, harmless while undisturbed. Then Ouvry and his party returned to the shore. Ouvry described the new mine and explained what he proposed to do. This was the first stage of the dismantling, to remove the detonator, and, as it was hoped, to make the mine dead and safe to handle. It was important that Ouvry should indicate what he intended to meddle with, so that, if he were blown to pieces, the Navy would know, on encountering the next mine, that the part which Ouvry had

touched first should be touched a little later in the proceedings. A grim business! Second Detonator OUVRY removed from the outside of the mine what he recognized as a detonator, designed to set off the mine if it struck a hard object on its journey to the bottom of the sea. It was the impact detonator in the delicate magnetic apparatus which can be operated only by the presence in the vicinity of a strong magnetic force, represented by a metal-built vessel passing overhead.

Perhaps it was fortunate that Ouvry took the more obvious thing first—the external impact detonator—because the mine was then considered to be harmless, and at next low-water it was retrieved and was jogged along the road in a two-wheeled bin at the tail of a box car, bound for the torpedo and mine research station at Portsmouth. The crowding experts then discovered the magnetic detonator, and Hitler’s secret was exposed. Naval establishment men, assisted by the leading scientists of the country, then set about finding the antidote. Somebody must have had an inspiration, for, as I have said, the method of demagnetizing ships was evolved in less than three months, and, when the announcement was made on March 8, the additional news was given that already hundreds of British iron and steel ships had been fitted with the immunizing waistline belt. Warships, merchantmen, destroyers, trawlers, mine-sweepers, and yachts have been so equipped, and not one has been lost by explosion of a magnetic mine. The “antidote” is believed to be 100 per cent, effective.

The Navy keeps its secrets well. It was only when the world’s largest liner, the 86,000 ton Queen Elizabeth, arrived in New York on March 7 that “stickybeak” dockside reporters observed from the landing-stage (nobody was allowed on board) that the majestic liner had a queer wire round her upper bulwarks. Somebody admitted that it was a non-magetic girdle. It consisted of an ordinary insulated wire “snaked” round the vessel at the level of the sheer strake, the upper line of the hull. A mere nothing, as one might say, but this turned out to be the secret D.G. girdle, a wire electrified from the ship’s dynamos in such a way as to neutralize the magnetism of the ship, so that she would have no magnetic field, and would not give off any magnetic impulse that would attract the delicately suspended needle of the

magnetic mines and so operate the electric detonator.

The naming of the equipment—as the D.G. or De-Gaussing equipment—was in the typical naval manner. Gauss is the unit of magnetic flux. Probably nobody thought to remember that Gauss was the great German mathematician whose magnetic discoveries are commemorated in much magnetic phraseology. The naval correspondent of The Times naively remarked, “The name has no reference to anyone connected with the invention of the equipment.” Even those who do know that the volt, the ampere, and the ohm perpetuated the names of pioneers in electrical research, were not prepared to affirm or deny that Gauss might have been a Scandinavian engineer of sorts, but insisted “The gadget is allBritish.”

Safety for Ships MR Churchill recently admitted cautiously that something was being done to cope with the magnetic mine, which did seem to be rather a deadly factor in the sea war. It was too early for him to tell the facts. Probably the Navy would have remained silent indefinitely but for the keenness of American newspaper men in finding out about the Queen Elizabeth. We who write for the papers are constantly reviling the censorship, not only for its inconsistencies, but for its failure to give out heartening items of news which are already in the possession of the enemy. But here a case can be made out for reticence. Germany was spending vast sums on these intricate mines, with their 6501 b of high explosive; her submarines and seaplanes were taking grave risks in coming close to the British shores to plant these death-dealers :n the shallow, frequented waters. Why let the enemy know that his work was being done in vain? Why tell him that all his eggs would be addled, that they would remain harmlessly stuck in the mud, that no magnetic impulse henceforward would pass to cause the great splash intended to send combatants or

innocent fishermen to their doom? Within a few weeks every British ship afloat will have the De-Gaussing equipment. It is cheap to instal and cheap to run. considering the immunity it gives. The Queen Elizabeth was fitted in a fortnight, at a time when the navy men were not thoroughly sure of their technique. Vessels are now being fitted in “from 24 hours to 24 days”; four days is probably the standard time for a medium-sized ship.

Blow for Germany THE clever Germans who conspired to use the ship’s magnetism for her own destruction doubtless thought, as Hitler said, that this weapon had no counter-measure. Rather, he said that it was a weapon with which Germany could not be attacked, and that sounded sinister. It turned out that British scientists know something about the magnetism of ships. As The Times says: “It is gratifying to realize that those who devote their talents to applying the methods of science to preservation are even more brilliant than the apostles of destruction.” Every navigator knows the bother of correcting his magnetic compass. Few laymen and not many sailors, however, realize that magnetism is hammered permanently into the hull of a ship during its construction. Small ships have different magnetic capacities. This may be because they were built in different latitudes, or because their keels were laid at different angles to the magnetic pole; then the nature of the ship’s cargo may mean some modification o f the De-Gaussing. Here we approach the barrier marked “secret.” How a plain insulated electrified wire round a ship makes it non-magnetic may be quite simple to the expert; details are not to be told to Germany. But the physics master might have quiet fun with his form, and the brilliant boys might suggest developments. For instance, there was no reply forthcoming when a London pressman asked: “What about Gaussing our planes, so that they can set off the magnetic mines harmlessly?”