How is the Galileo thermometer readings

According to Galileo & middot; Ng riley ( 伽利略) In the early 17th century invention of thermometer, we are now common thermometer on his desk is called the Galileo thermometer. It is a simple and accurate thermometer, is now mainly used as decorations. Galileo thermometer consists of a glass tube filled with water and a few floating bubbles. These bubbles is full of color liquid mixture of glass ball. The liquid mixture may contain alcohol, possibly just water containing food pigment. Each glass bulb connected with a small metal tag indicating temperature. Symbols engraved with a number on the label and temperature. The balance of the fact that the metal label are calibrated. The weight of each label are slightly different with the other. As a result of these glass bubble is blow made by hand, they have different size and shape. The glass bulb is through to join a certain amount of liquid which has the same density method for calibration. Therefore, after weight of label on the connection, the density of each glass bulb ( The quality of volume And other glass bubble is slightly different, and the density of all glass bubble is very close to the density of water around them. The basic principle of Galileo thermometer is as the change of outside air temperature thermometer, temperature of water around the glass bulb will change too. But as the change of water temperature, water can expand or contract, its density change. So, in any given under the density of some glass bulb to come, while others will sink. Sinking the most glass bulb which indicate the current temperature.