SPHERICAL ATMOMETER CUPS 



A spherical evaporating surface, 5 cm. 

 in diameter, presenting the same external ex- 

 posure in all directions, with glazed cylindri->- 

 oal 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 cylindrical 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 supplied either standardized or unstandardized. Stand- 

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

 cannot be satisfactorily standardized to the cylindrical 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). 



Standardized White Spheres, $2.00 each, $18.00 per ten 

 Unstandardized White Spheres, $1.75 each, $15.00 per ten 



THE PLANT WORLD 



TUCSON, ARIZONA 



BOTANICAL PAPERS FOR SALE 



The prices given include postage. Address S. B. PARISH, 



San Bernardino, Cal. 



Torrey, Bot. Whipple Surv. $1.75; PL Frem. $1.25. 



Gray, Char. New Comp. $0.50; Aster and Solidago $0.75.; List of Writings $0.30. 



Engelmann, Cuscuta $1.00; True Grapev. $0.25; Some Add. N. A. Flora $0.25. 



Watson, Contrib. V. $0.25; IV. $0.50; VII. $0.25; X. $0.50. 



Greene, W. Am. Oaks $5.00; W. Amer. Red Cherries $0.20; Diag. Aragall. $0.25; 

 Platystemon $0.30. 



Vasey, W. Amer. Grasses, Pt. 2 $1.00; Grasses Pacific Slope, Pts. 1 and 2 $2.50. 



Merriam, Dist. Trees and Shrubs, S. Cal., Utah &c. $0.30; Distrib. Cactaceae &c. 

 $0.30; N. A. Fauna No. 16 (Mt. Shasta) $1.00; No. 7 (Death Valley) $1.50. 



Coville, Bot. Death Val. $1.50; New Plants S. Cal. &c. $0.35. 



Hall, Compositae S. Cal. $2.25. 

 Hasse, Lichen Flora S. Cal. $0.35. 

 McLatchie, Flora Pasadena $1.25. 

 Bull. Cal. Acad. 1 $0.65; 3 $1.00. 

 Coulter, Bot. W. Tex. Pts. 1 and 2 $1.25. 

 Small, Mimosaceae S-E. U. S. $0.30. 

 Oenothera and Segregates $0.25. 

 Rydberg, Oaks Contin. Divide $0.50. 

 Report Mo. Bot. Garden, Vol. I. $0.60. 

 Chandler, Rev. Nemoph. $0.30. 

 Robinson, N. Amer. Alsineae &c. $0.40. 



Sandberg, Flora Sand Hills Neb. $0.25. 



Norton, Tithymalus $0.75. 



Dudley Memorial Volume $0.35. 



Hill, Forest Conditions Porto Rico $0.30. 



Jepson, Mt. Wliitney $0.25. 



Piper, N. Amer. Festucae $0.30. 



Dodge, Uncult. Bast-fibers U. S. $0.30. 



Underwood, Selaginella rupestris $0.25. 



Lemmon, Oaks of the Pacific Slope $0.35. 



Forest Influences $0.25. 



