VI CONTENTS. 
GENERAL APPENDIX. 
Page. 
Modern theories of the spiral nebulae, by Heber D. Curtis 
A determination of the deflection of light by the sun's gravitational field, 123 
from observations made at the total eclipse of May 29, 1919, by Sir 
F. W. Dyson, A. S. Eddington, and C. Davidson 133 
Wireless telephony, by N. H. Slaughter 177 
Radium and the electron, by Sir Ernest Rutherford 193 
The "HD-4." A 70-miler with remarkable possibilities developed at 
Dr. Graham Bell's laboratories on the Bras d'Or Lalies, by William 
Washburn Nutting 205 
Natural resources in their relation to military supplies, by Arthur D. 
Little 211 
Glass and some of its problems, by Sir Herbert Jackson 239 
The functions and ideals of a national geological survey, by F. L. Ran- 
some 261 
The influence of cold in stimulating the growth of plants, by Frederick 
V. Coville 281 
Floral aspects of British Guiana, by A. S. Hitchcock 293 
Milpa agriculture, a primitive tropical system, by O. F. Cook 307 
On the extinction of the mammoth, by H. Neuville 327 
A preliminary study of the relation between geographical distribution 
and migration, with special reference to the Palaearctic region, by 
R. Meinertzhagen 339 
The necessity of State action for the protection of wild birds, by Walter 
E. Collinge 349 
Glimpses of desert bird life in the Great Basin, by Harry C. Oberholser__ 355 
The Division of Insects in the United States National Museum, by J. M. 
Aldrich 367 
The seventeen-year locust, by R. E. Snodgrass 381 
Entomology and the war, by L. O. Howard 411 
Two types of southwestern clifE houses, by J. Walter Fewkes 421 
On the race history and facial characteristics of the aboriginal Ameri- 
cans, by W. H. Holmes 427 
The opportunity for American archeological research in Palestine, by 
James A. Montgomery 433 
The differentiation of mankind into racial types, by Arthur Keith 443 
The exploration of Manchuria, by Arthur de C. Sowerby 455 
The origin and beginnings of the Czechoslovak people, by Jindfich 
Matiegka 47I 
Geographic education in America, by Albert Perry Brigham_ 487 
Progress in national land reclamation in the United States, by C. A. 
Bissell 497 
Richard Rathbun, by Marcus Benjamin 523 
A great chemist : Sir William Ramsay, by Cli. Moureu 531 
