         @logger.debug("Initializing")
 
         @density = 10  # The density of the environment's medium. 
+        @gravitationalConstant = 0.5
 
 
     # Update the elements with the effects of the given number of milliseconds

        for element in elements

            # Find the net force on the element.
            forces = [element.velocity(), @drag(element)]

            resultant = forces.reduce (t, s) -> t.sum(s)    #FIXME: not portable



        return element.direction.scale(-m)


    # Return the force of gravity on the given element.
    #
    # @param element {Object} 
    gravity : (element) ->
        force = new timber.Vector(0, @gravitationalConstant)
        

# 
# An abstract base class for any drawable thing.
