The end of the cylinder was being screwed out from within.  Nearly
two feet of shining screw projected.  Somebody blundered against me,
and I narrowly missed being pitched onto the top of the screw.  I
turned, and as I did so the screw must have come out, for the lid of
the cylinder fell upon the gravel with a ringing concussion.  I stuck
my elbow into the person behind me, and turned my head towards the
Thing again.  For a moment that circular cavity seemed perfectly black.
I had the sunset in my eyes.