During war-time belligerent countries spend a great deal of time and money in the endeavour to intercept and read the messages of each other.
I was interested, therefore, to discover the other day a method which was used successfully during the last war to intercept cable messages between Great Britain and America on the cables which run from Ireland across the Atlantic.
It was impossible to "tap" the cables on land, so a new plan had to be devised. This took the form of "tapping" by submarines. While the submarines could not directly "tap" the cable on the sea bed, they could, by laying several hundred feet of wires along the sea bed near the cable, read the messages by induction.
By this time I suppose that new methods have been found for ensuring the secrecy of the cables - and, presumably, new ways of "tapping" them also are being sought.
The Irish Times, March 27th, 1940.