SPHERICAL ATMOMETER CUPS 



A spherical evaporating surface, 5 cm. 

 in diameter, presenting the same external ex- 

 posure in all directions, with glazed cyUndri- 

 cal neck 3 cm. long and 2 cm. inside diameter. 

 They are composed of very resistant material, 

 of proper porosity for atmometric work, and 

 are to be mounted on rubber stoppers as in 

 the case of cyUndrical cups. The spheres may be cleaned with brush and distilled 

 water, may be treated with acid, and even heated to red heat. They should thus be 

 capable of many years of use, without permanent alteration of the coefficient. They 

 are not easily broken. 



These new spheres are suppHed either standardized or unstandardized. Stand- 

 ardization is carried out with reference to a newly adopted spherical standard; spheres 

 cannot be satisfactorily standardized to the cyUndrical standard cup. Therefore 

 readings from spheres are not satisfactorily reducible to terms of readings from cylin- 

 ders (see Plant World, Vol. 18, pp. 21, 51, 95, 143). 



Unstandardized White Spheres, $2.25 each, $20.00 per ten 

 • Standardized White Spheres, $2.75 each, $25.00 per ten 



THE PLANT WORLD - - TUCSON, ARIZONA 



A MAP OF THE 

 VEGETATION OF THE UNITED STATES 



A colored map 20 x 12 inches in size showing the 18 major types of vegetation 

 in the United States. Prepared hy Di . Forrest Shreve, and reprinted fi(jni the 

 Geographical Review. Accompanied Ijy a !)rief descriptive text. 



Text, with Folded Map $.50 each, $4.00 per ten 

 Text, with Rolled Map $.60 each, $4.10 per ten 



THE PLANT WORLD Tucson, Arizona 



KODAK FINISHING 



Wtf Guarantee to i^et the best possible results from your 



exposures. Mail orders attended to promptly. 



Catalogue and Price List Free 



. The Smith Sporting Goods Company 



TUCSON, ARIZONA 



