In the first part of this paper, the structure and function of rain and evaporation gauges with a rectangular opening are described,which appeared in Ceyuan Tujie (A Diagrammatic Study of Measuring Circles) written by Dai Yuan (1761) during the reign of Emperor Hong Li (Qian Long).Then the two gauges are compared with those used in Europe and America before and after the year of 1761. In the secondpart the evolution of the gauges with their openings changing from therectangular to circular form is examined and the nature of the book Ceyuan Tujie is analyzed.It is concluded that the gauges recorded inCeyuan Tujie were introduced from Paris to China by the Jesuits-Pretre Francais and used for rainfall and evaporation measurements in Beijing, the capital of China in the Qing dynasty just before the year of 1761. Though the gauges were not invented by the Chinese, the record is still of significance in the history of meteorological instruments in China.