         # Update the state of the world.
         now = new Date()
         elapsed = now - @timestamp
-        @environment.elapse(@elements, 1)
+        @environment.elapse(@elements, elapsed)
         @canvas.clear()
         @canvas.render(@elements)
         @timestamp = now

        # Loop again, when the stack clear.
        setTimeout () =>
            @.loop()
        , 10

    add : (element) ->
        @elements.push(element)

    # Run the engine's event loop.
    loop : () ->
        # Stop, if so desired.
        return if not @continue
