4 i'^ 5 



PROCEEDINGS 



OF THE 



American Philosophical Society 



HELD AT PHILADELPHIA 



FOR PROMOTING USEFUL KNOWLEDGE 



Vol. L. July-August, 191 i. No. 200. 



CONTENTS. 



Symposium — The Modern Theory of Electricity and Matter. 



I. The General Principles. By Daniel F. Comstock 321 



II. Radioactivity. By Bertram B. Boltwood 333 



III. The Dynamical Effects of Aggregates of Electrons. By Owen W. 



Richardson 347 



IV. The Constitution of the Atom. By Harold A. Wilson, F.R.S 366 



The High Voltage Corona in Air. By J. B. Whitehead 374 



Disruptive Discharges of Electricity Through Flames. By Francis E. Nipher 397 



The Desert Group Nolineae. By William Trelease 405 



Isostasy and Mountain Ranges. By Harry Fielding Reid 444 



A Fossil Specimen of the Alligator Snapper (Macrochelys temminckii) from 



Texas. By Oliver P, Hay 452 



PHILADELPHIA 



THE AMERICAN PHILOSOPHICAL SOCIETY 



104 South Fifth Street 



1911 



