Source : Webster's Revised Unabridged Dictionary (1913)

Down \Down\, prep. [From {Down}, adv.]
   1. In a descending direction along; from a higher to a lower
      place upon or within; at a lower place in or on; as, down
      a hill; down a well.

   2. Hence: Towards the mouth of a river; towards the sea; as,
      to sail or swim down a stream; to sail down the sound.

   {Down the country}, toward the sea, or toward the part where
      rivers discharge their waters into the ocean.

   {Down the sound}, in the direction of the ebbing tide; toward
      the sea.