April, '14] SHELFORD: ATMOMETERS 249 



THE USE OF ATMOMETERS TO MEASURE EVAPORATION 

 IN THE STUDY OF INSECTS 



By V. E. Shelford 



The porous cup atmometer or evaporimeter, was first designed by 

 Babinet in 1848. Subsequently, it was independently devised by 

 several workers. B. E. Livingston was one of the last of these and his 

 instrument has become the standard in this country and f]urope. It 

 consists of a cup of porous baked clay about 5 inches long and 1 inch in 

 diameter. The cup is filled with water and a rubber stopper contain- 

 ing a small glass tube is inserted into the opening. It is placed cork 

 end down and the glass tube is connected with a bottle or other reservoir 

 of water. As water evaporates, the cup remains full and water is with- 

 drawn from the reservoir. The amount withdrawn- is the amount of 

 water evaporated. Differences in evaporation are shown correspond- 

 ing to changes in temperature, air moisture, air movement and air 

 pressure. Black, brown or other colored cups are used to determine 

 the effect of light. In sunlight, the colored cups show a greater amount 

 of evaporation than the white ones. Cups of the color of the insects 

 studied could probably be used to advantage. 



The instruments have been found indispensable by numerous 

 persons attempting to study and control the complete environment. 

 They are used both in cages and in the field where they are the only 

 instruments that record the effect of wind movement and exposure to 

 the sun as well as temperature, etc., in terms of any physiological 

 significance. Rain correcting device has already been invented by 

 Livingston. The cups may be obtained from the Plant World, Tucson, 

 Ariz., and details as to their use can be obtained from the files of that 

 journal for 1910 and 1911. Reasons for the importance of the measure 

 of evaporation based upon the study of literature, and some experi- 

 ments are given by the writer elsewhere in the Association's Journal. 



Prof. J. H. Comstock, for thirty nine years instructor and professor of entomology 

 at Cornell University, has resigned and will retire frona active duties at the close of 

 the present academic j;ear. The following expression of appreciation by the Board 

 of Trustees was made public: "In accepting the foregoing resignation the trustees 

 congratulate Professor Comstock on his long, honorable and fruitful service to Cornell 

 University, with which as student and teacher he has been associated almost without 

 interruption since he matriculated as a freshman, and they bear gi-ateful testimony 

 to his success in teaching and in inspiring students and also in scientific investigation, 

 for the continuance of which they trust his health and energy may be preserved for 

 many years to come to the honor of his alma mater and the advancement of truth and 

 knowledge." 



