THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



?' 





Art. XYIII. — The Discharge-current from a Surface of large 

 Curvature / by John E. Almy, Ph.D.,, Instructor in Physics, 

 University of Nebraska, Lincoln. 



1. The discharge of electricity from a surface of large 

 curvature has been studied by Warburg,* and others. f Inas- 

 much as the nature and form of 



the discharging surface, when a 

 point, or pointed wire, is used, is 

 necessarily more or less prob- 

 lematic, it seemed of interest to 

 study the discharge from a fine 

 wire of uniform dimension. 



The discharge from a platinum 

 wire of very small size to a con- 

 centric, circular cylinder has been 

 the subject of study. 



2. The discharge apparatus is 

 shown in fig. 1. The brass cylin- 

 der, C, cemented to the glass 

 plate, is further insulated by the 

 supports of sealing-wax, s, s. 

 The discharge wire, passing 

 through the capillary tube, T, 

 embedded in paraffin, hangs ver- 

 tically, stretched by the weight 

 of a short piece of tube, T', in 

 which its lower end is embedded, j 

 Paraffin discs, D, D', serve to ] 

 keep the wire at the center of 



the cylinder. The gas is removed and supplied by tubes P and 



* Warburg, Wied. Ann., lxvii, p. 82 ; Ann. d. Phys. (4), ii, p. 295. 

 f Sieveking, Ann. d. Physik. (4), i, p. 299, etc. 



Am. Jour. Sci. — Fourth Series, Yol. XII, No. 69. — September, 1901. 

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