While the cylindrical container is rotating around the central axis, the liquid contained in it is driven to rotate around the same axis at the same time. At a relatively stable state that the rotational speed of the liquid is nearly constant, a paraboloid can be formed on the surface of the liquid due to the combined action of gravity and the centrifugal force. Since the optical focal distance of the paraboloid is only related to the local acceleration of gravity and the rotate speed of the container, this equipment can be used to measure the g of the local place. What is more, the optical focal ability enables it to be used as the main reflector of a simple Newtonian-Focal-System telescope. And the lateral magnification of this telescope is also a property that can be measured.