178. Philip Westwell also remembered that after the runway was complete they needed a way of denying the runway to Warsaw Pact forces should Jever be overrun.   These were known as "Retardation Measures".   Every 100 yards down the runway a German contractor bored a hole across the 50 yard width of the concrete.   See the next picture of this being done.   The runway, because of the extremes in the weather in North Germany, had been laid on an unusually thick layer of sand, about 1 metre, to provide excellent drainage and to avoid waterlogging and freezing.   The hole was about at the level of the bottom of the sand layer.   On either side they built a brick chamber about 8 ft by 5 ft and about 6ft deep.   Each one had a manhole cover on the top and one such cover was found by Philip and is shown in the picture.   The plan was to allow a man in each chamber to feed Bangalore torpedoes, (a form of mine 4 ft long by 8 inches in diameter), into the tube.   To span the runway would take about 30 to 40 torpedoes in each tube.   Ahlhorn was also equipped with these measures. (Thanks to Philip Westwell.)