Before revision: By bending the ends of the tube back towards the center of rotation, a shift of the liquid away from center will result in the water level in one end of the tube rising and thus increasing the pressure in that end of the tube, and consequently returning the water to the center of the tube.
After revision: By bending the ends of the tube back towards the center of rotation, a shift of the liquid away from center will result in the liquid level in one end of the tube rising and thus increasing the pressure in that end of the tube, and consequently returning the water to the center of the tube.