proceedings: philosophical society 73 



BIOLOGICAL SOCIETY OF WASHINGTON 



The 576th regular and the 38th annual meeting of the Society was 

 held at the Cosmos Club, Saturday, December 15, 1917; called to 

 order by President Hay at 8 p.m.; 19 persons present. 



The annual reports of officers and conmiittees were received, followed 

 b}" the election of officers for the year 1918. The results of the election 

 are given herewith : President, J. N. Rose ; Vice-presidents, A. D. Hopkins, 

 H. M. Smith, Vernon Bailey, Ned Hollister; Recording Secretary, 

 yi.W. Lyon, Jr.; Corresponding Secretary, W. L. McAtee; Treasurer, 

 Ned Dearborn; Members of Council, J. W.Cjidliiy, William Palmer, 

 Alexander Wetmore, E. A. Goldman, A*. S. Hitchcock. President 

 Rose was nominated by the Society as a vice-president of the Washing- 

 ton Acadeni}' of Sciences. 



President Rose appointed as Committee on Publications for 1918: 

 C. W. Richmond, N. Dearborn, W. L. McAtee, J. H. Riley; as 

 Committee on Communications: William Palmer, Alexander Wet- 

 more, R. E. Coker, L. 0. Howard, A. S. Hitchcock. 



M. W. Lyon, Jr., Recording Secretary.^ 



PHILOSOPHICAL SOCIETY OF WASHINGTON 



The 793d meeting was held at the Cosmos Club October 27, 1917; 

 President Buckingham in the chair; 27 persons present. 



Messrs. J. T. Tate and P. D. Foote gave an illustrated paper on 

 Critical potentials for electrons in metallic vapors. The subject matter 

 presented was published in this Journal (7: 517. 1917). 



Discussion: The paper was discussed by Messrs. Loeb, Silsbee, and 

 Becker. 



By invitation Mr. S. J. Crooker gave an illustrated paper on Experi- 

 ments on direct-current corona. Electrical discharges in gases at pressures 

 near that of the atmosphere may be divided into five classes: dark, 

 glow, brush, spark, and arc discharges. Corona is a glow or brush dis- 

 charge which appears on wires at high potentials indicating energy dis- 

 sipation to the surrounding gas. Engineering experiments on the 

 alternating-current corona have led to a revolution in the design and 

 construction of high-potential transmission lines, machines, transformers, 

 and insulators. Scientific investigations, especially on the direct-current 

 corona, have led to an explanation of the phenomena observed. 



A review was given of investigations made at the University of 

 Illinois on the direct-current corona under various conditions. The 

 corona discharge has been found to be a complicated function of 

 the applied voltage; kind of gas and its pressure; size, shape, spacing, 

 condition, and material of wires; temperature; humidity; etc. 



The characteristic discharge is a uniform layer of glow for the positive 

 wire and evenly spaced beads or brushes for the negative wire. The 

 critical voltage increases with the radius of the wire and the gas pressure 

 and is different for the positive and negative wires. A slight increase in 

 pressure due to ionization occurs on sudden application of potential to 



