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Re: Surveying errors, and misalignment of tunnels There must be many instances of misalignment. Three I have come across were as follows: (1) At Bretby No. 3 colliery, South Derbyshire, where I went for vacation work in 1950, a new longwall face had been breasted out from the main gate heading. As the face was finished to full width before the tailgate had reached it, a tailgate drive was driven back from the end of the face, intended to meet the oncoming tailgate development. The levels were wrong, and the two tunnels ovelapped by 20 yards before the error was discovered. The lad delivering new pit props to the face had to stop his pony in the upper gate, throw the props down through a hole in the floor, them climb down himself, load them on another trolley, and push them up to the face by hand. Steps were in hand to rerip the tunnels so he could take his pony all the way to the face but, in the meantime, coal production was needed and the face had started coaling. I did notice, as we crawled though the face, that there was a surveyor's benchmark painted on part of the face conveyor. As this was moved forward on every afternoon shift to keep up with the advancing face, it did not seem to me to be a very reliable basis from which to take levels. (2) When I was in the Royal Engineers tunnelling unit in Gibraltar during my National Service, the principal tunnel we were working on in 1953/54 was a "cross-cut" needed to join up two tunnels which had been driven during the War, then abandoned uncompleted in 1945. One had been driven from the east side of the Rock, the other from the West. Several drawings in the filing cabinet showed the progress of these along a common centre line yet, when they were resurveyed, the one from the west proved to have been driven five degrees off line. We needed a 400 foot dog-leg to link the two tunnels. (3) On a coach tour with fellow students round Cornwall in 1952 withJack Trounson as guide, he took us to a pub in Mousehole where one of the "pictures" on the wall was a mine plan. This, Jack explained, had been presented as evidence in a public hearing, showing that the mine manager had got his survey wrong. Thinking his mine was working a different vein to that in an abandoned, flooded mine nearby, he had got his dialling wrong. Some of his men holed through into the flooded mine, and they and several others were drowned. Tony Brewis %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%