Cancellation of the gravitational force is a long favorite
experiment of sci-fi writers, but as far as in our knowledge,
nobody considered the case of gravity force acting in the
horizontal direction. “Gravitus Horizontus” is the magic spell
used by Magica de Spell in A Matter Of Some Gravity. She learned
it in a magicians’ meeting in Lucca (probably referring to Lucca
Comics): the spell cause a temporary modification in gravity’s
arrow against people affected by the spell. In this case Donald
and Scrooge experiment a horizontal gravity, toward the walls of
the money bin. Don Rosa doesn’t specify, from time to time, if
there is a new center of gravity, so that walls, palaces,
mountains attracted Donald and Scrooge with a horizontal force.
More likely it is the terrestial gravity which acts again, after
a local rotation of the versus of the force, as suggested by
Donald Duck’s quotation while the two ducks are in Scrooge’s
office: This furniture only looks like it’s nailed down! I’m too
heavy for it! Later Don