Hours and hours passed, with nothing to do but keep the...

Hours and hours passed, with nothing to do but keep the compass on its course and the plane on a level keel. This sounds easy enough, but its very simplicity becomes a danger when your head keeps nodding with weariness and utter boredom and your eyes everlastingly try to shut out the confusing rows of figures in front of you, which will insist on getting jumbled together.