How Galileo floating ball thermometer readings?

Galileo thermometer is an Italian scientist Galileo developed on the basis of the principle of material heat bilges cold shrink temperature measuring device. Designed according to the principle of object density changing with temperature of stained glass bulb thermometer, also called Galileo thermometer. Galileo thermometer readings although there is no professional precision thermometer, careful observation will find that small glass ball up and down in the tube arrangement is regular, the highest temperature drop ball at the top, the lowest in the bottom, and whether or not the ball, or sink or float, both from the top down according to drop temperature descending order. When all balls are still in the glass tube, not up and down, all the floating ball in the bottom of a small ball drop temperature is measured by the current temperature. Sometimes central glass tube with a static levitation ball, then it's drop temperature close to room temperature. But most of the time in the middle of the floating ball is an illusion, because actually the environment temperature change, causing the suspension of the glass ball is slowly float or sink, can make the person think static because too slowly. Different from common use of thermometer, Galileo thermometer is using the density difference principle. Is at a certain temperature, the small ball's overall density is greater than the transparent liquid density in the tube, it is the buoyancy of transparent liquid is less than its gravity, ball sinking; On the other hand, if the overall density of small glass ball less than transparent liquid density in the tube, it is the buoyancy of transparent liquid is greater than its gravity, small ball float. When the transparent liquid in the tube temperature change, its density will change. So different ball float or sink to a equal position with the surrounding liquid density. If the overall density of control the ball, make the lowest ball row overall density from above, the highest row at the bottom, thus forming temperature scale, used to indicate the temperature. So if it has a profound understanding and the interest, Galileo thermometer is mainly used for indoor environment decoration or as gifts, collection.