“DE-GAUSSING”

Grey River Argus, 15 April 1940, Page 10

“DE-GAUSSING”

Protection for Ships ANSWER TO MAGNETIC MINE “This war is being fought by the scientists” is one of the current sayings. It is well known that much of the best brains of the world have been enlisted to make weapons more deadly; on the other hand, they are occupied also in defensive work. Sometimes their work, on both sides, comes into sudden prominence; as, for instance, in the case of the magnetic mine, with which the Germans “sprang a surprise” upon the British marine. The immediate reaction to this innovation was a vigorous scientific investigation to find means of destroying the mines or making them ineffective. As the mines are designed to be fired by the effect upon them of the magnetic qualities of an iron ship, an obvious counter-measure was to patrol infested water with a high-ly-magnetic sweep, which would be far more likely to trip the mine than a feebly-magnetic ship. This was, of course, done—with what results has not been disclosed.

A second attack on the problem is to make ships immune as far as'possible to the magnetic mine danger, and this also has been attempted—again with an undisclosed degree of success.

Cabled messages from New York reporting the safe arrival of the Queen Elizabeth, the greater sister of the Queen Mary, after a secret run across the Atlantic, referred to a system of protection against the menace of magnetic mines, using the new term “degaussing.” Assurances that scientists had worked upon the problem were given by members of the British Cabinet soon after the first magnetic mines were sown, but what they had done and were doing was not so much as hinted at.

The Queen Elizabeth certainly had special protective equipment strung round her enormous hull when she slipped away from Clydeside, Scotland, on the morning of March 2 and arrived unexpectedly, as far as New York knew, early on the morning of March 7. So well was the secret kept that the New York welcome to the great ship was given by a lone refuse disposal barge and was acknowledged by three booming hoots; but the news was out, and within minutes the New York newspaper world was waiting at the barriers of Pier 90, North River, where the Queen Elizabeth joined 1 company with the Queen Mary, the [ Mauretania, and the Normandie. | Captain John Townley answered a ' rush of questions freely, but while osknowledging his friendly response, New York newspapers which arrived by the last mail were a good deal re- j gretful that though he did reply, he

gave them not so many facts;, they built up a long story upon them, nevertheless. The anti-mine device, a system of cabling hung all round the upper part of the hull, was so obvious that questions as to its purpose could not be passed over. Captain Townley admitted at once that it was to counter the threat of the magnetic mine, and gave it a name as a “de-gaussing” device.

The gauss is the unit of measuremeant of magnetic force, and to “degauss” is to destroy magnetic force; in the ideal the steel ship so de-gauss-ed would be as dead to the magnetic mine as a wooden hull. The captain made no claim that the system did protect the great ship; he simply said that that was the purpose of the cabling, that it was charged on the dash across the Atlantic, and that the system was secret. Photographs of the Queen Elizabeth show the cabling clearly, heavy in diameter and heavily sheathed, held by metal brackets each few feet, just clear of the hull and below the overhang of the central sections, then rising almost to the top of the hull at bow and stern. A CONSPICUOUS FITTING. The anti-mine device said the “New York Herald Times,” must have cost thousands to install; it immediately caught the eyes of all hear the pier. While the ship’s speed, after a con-' voy of four destroyers left her at the end of the first day, took care of the danger of enemy U-boats, the new electrical equipment was expected to nullify the effect of sunken mines over which she might pass. It was explained that the cables, suspended free of the hull itself, just below the overhang, set up a field of electric force that offset the magnetic quality of the hull, on which the magnetic mines depend for their deadliness.

A similar device had been tried in a minor way on the Cunarder Scythia on her last voyage to New York, but received scant attention.

The liner carried no guns and no other defence, unless one counted the compact steel shelter houses, or pillboxes, in the wings of the bridge and also on the after-bridge. Similar shelter houses have been installed on other British merchantmen in the Atlantic service, and officers can stand in them to direct manoeuvres of the ship if she is attacked by machinegun or small shell fire.

That is as far as the combined efforts of New York newspapermen were able to penetrate the secret ol the anti-mine protection in a full day and night of certainly intensive in- < uiry and effort. They could never have got that far but for the obvious fact that heavy sheathed cabling running the entire length of a 1030-foot liner on precisely spaced and placed brackets was there for some use other than ornamentation, and Captain Townley, preferring to meet speculation at least part way, answered frankly that the Queen Elizabeth,

and a considerable number of other British liners and larger ocean-going vessels, were equipped with “de-gaus-sing” apparatus evolved by scientists to meet the threat of the newest Nazi sea outrage. SIMPLE IN PRINCIPLE. The de-gaussing device is, in fact very simple and its principle is no secret. The sensitive portion of the firing gear of the mine is a delicate-iy-balanced “needle” or group of needles, not unlike that of a compass; and it remains in a stationary position as long as the surrounding magnetic conditions remain unchanged. Those conditions are due to the earth’s magnetism. The approach of an iron ship disturbs them, and the needle tilts. The ship behaves like a weak magnet. But an electric current passing through a coil of wire also generates a magnetic force; and by rigging a coil round the ship and energising it from the ship’s power supply it is possible to generate magnetism which exerts a force on the mine’s mechanism, equal and opposite to that of the ship’s hull.