The Top of a Narrow Chimney                            -      -      - 
(-------------------------------------------------)     - <---(M)---> E
                                                        -      -      -

You are standing at the top of a very tall shaft that leads down into
another chamber below.  Climbing down it will require a great deal of
caution and patience, since the chimney is just wide enough for you to
squeeze into.  You'll have to brace yourself with your arms and legs, slowly
inching down in order to avoid slipping.