VI CONTENTS. 
GENERAL APPENDIX, 
Modern theories of the spiral nebulae, by Heber D. Curtis________-_---_~ 
A determination of the deflection of light by the sun’s gravitational field, 
from observations made at the total eclipse of May 29, 1919, by Sir 
Ro Weibyson, A. S.pHadineion, andy!) aera som as hee ee ee 
Wireless: telephony; by .N;H Slaughters 22 28 ee ee eee 
Radium and the electron, by Sir Ernest Rutherford___-_-______________ 
The “HD-4.” A 70-miler with remarkable possibilities developed at 
Dr. Graham Bell’s laboratories on the Bras d’Or Lakes, by William 
Sp EIS OY GLU Wg 0 Deol 6) 6 Yetta a spr ae es 5 eth a eo boo 
Natural resources in their relation to military supplies, by Arthur D. 
1 Cpl Ke resem a a a ae Nalgene pea ih su idiphe Ms Lh late a ara iio cee se iicpeyeag elf 
Glass and some of its problems, by Sir Herbert Jackson_-__-_-_-____-___ 
The functions and ideals of a national geological survey, by F. L. Ran- 
The influence of cold in stimulating the growth of plants, by Frederick 
Aap OOO KS RAN A Wh et NE IS Soe RS NG UAL OTS ER tN 
Floral aspects of British Guiana, by A. S. Hitchcock_______-___________ 
Milpa agriculture, a primitive tropical system, by O. F. Cook ___-______ 
On the extinction of the mammoth, by H. Neuville-____--________________ 
A preliminary study of the relation between geographical distribution 
and migration, with special reference to the Palaearctic region, by 
3 EME (NAYES BA 0 W250 A A RS NS un Ua Ne Sapna ey edi lc 
The necessity of State action for the protection of wild birds, by Walter 
1 SDP Gr oy Ue mee i ie Fy ee en la aaa eh one iene Sy 
Glimpses of desert bird life in the Great Basin, by Harry C. Oberholser__ 
The Division of Insects in the United States National Museum, by J. M. 
PENIICG BiG) epee gr ss en ibaa Nani A peal sna inn Atlee Aaa NAN ea Rete e Nk 
The seventeen-year locust, by R. H. Snodgrass__--____-____-__-_____-___ 
Hncomolosy sand: thenwat, byl OF ELOWATE 22 She 
Two types of southwestern cliff houses, by J. Walter Fewkes____________ 
On the race history and facial characteristics of the aboriginal Ameri- 
ELEN ONS Hn) Oar Vege fev) Era wo epee Nar pn ea agg YR Nye Toe AUP ae 
The opportunity for American archeological research in Palestine, by 
AEDT YY OS Ne IVETE TUNEL Yosser ay ge cer eel ee Ree 
The differentiation of mankind into racial types, by Arthur Keith_______ 
The exploration of Manchuria, by Arthur de C. Sowerby_-_-_---------_- 
The origin and beginnings of the Czechoslovak people, by Jindfich 
JA eel 20 fy ee patie mie nal asyacetee ki meee Aimee bbl rnchshurmahOrl pines cy 2Mnbe sul obE il thn Npinssats ely gi 
Geographic education in America, by Albert Perry Brigham ____-_______ 
Progress in national land reclamation in the United States, by C. A. 
1 BSC Hl pepe pea. fain Wace fet yc add ci ce at abl deg Mins bend tude gs SNe 
Richard Rathbun: by Marcus sen a mine eee ee eee 
A great chemist; Sir William Ramsay, by Ch. Moureu-_-_---_-.-.--_.—_.. 
