a few minutes later the feeling in the pit of my stomach receded and tnie asked that we all sit down , once this was done he gently rotated the two wheels either side of him and there was a jerk as our direction changed from going up to going forward , he opened a flap mounted on a post directly in front of him and scrutinised something that we could not see , i was later to have him explain to me that this device was called a compass and it showed with great accuracy which direction we were moving in .