100 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
REPORT FOR 1918. 
The report of the executive committee and proceedings of the 
Board of Regents of the Institution and report of the secretary, both 
forming part of the annual report of the Board of Regents to Con- 
gress, were issued in pamphlet form in December, 1918. 
Report of the executive committee and proceedings of the Board of Regents 
of the Smithsonian Institution for the year ending June 30, 1918. 13 pp. 
(Publ. 2529.) 
Report of the Secretary of the Smithsonian Institution for the year ending 
June 30, 1918. 101 pp. (Publ. 2487.) 
The general appendix of the report for 1918, which was in press 
at the close of the year, contains the following papers: 
1. The Discovery of Helium, and what came of it, by C. G. Abbot. 
2. An Account of the Rise of Navigation, by R. H. Curtiss. 
8. The Tornadoes of the United States, by Robert DeC. Ward. 
4, Wind Power, by James Carlill. 
5. A Tribute. Samuel Pierpont Langley: Pioneer in Practical Aviation, by 
Henry Leffmann. 
6. Modern Physics, by R. A. Millikan. 
7. The Experiments of Dr. P. W. Bridgman on the Properties of Matter When 
Under High Pressure. Introductory note, by C. G. Abbot. 
8. The problem of Radioactive Lead, by Theodore W. Richards. 
9. Sphagnum Moss; war substitute for cotton in absorbent surgical dress- 
ings, by George H. Nichols. 
10. History of Military Medicine and its Contributions to Science, by Col. 
W. P. Chamberlain. 
11. Some Problems of International Readjustment of Mineral Supplies as 
Indicated in Recent Foreign Literature, by Eleanora F. Bliss. 
12. Reptile Reconstructions in the United States National Museum, by 
Charles W. Gilmore. 
18. A Pleistocene Cave Deposit of Western Maryland, by J. W. Gidley. 
14. Paleobotany: A Sketch of the Origin and Hvolution of Floras, by Edward 
W. Berry. 
15. The Direct Action of Environment and Evolution, by Prince Kropotkin. 
16. The Law of Irreversible Evolution, by Branislav Petronievics. 
17. The Fundamental Factor of Insect Evolution, by S. S. Chetverikov. 
18. The Psychic Life of Insects, by E. L. Bouvier. 
19. Sexual Selection and Bird Song, by Chauncey J. Hawkins. 
20. Marine Camoufleurs and their Camouflage: The present and prospective 
significance of facts regarding coloration of tropical fishes, by W. H. Longley. 
21. Foot-Plow Agriculture in Peru, by O. F. Cook. ~ 
22. Sun Worship of the Hopi Indians, by J. Walter Fewkes. 
23. The League of the Iroquois and its Constitution: A constitutional 
league of peace in the Stone Age of America, by J. N. B. Hewitt. 
24, The Problem of Degeneracy, by H. F. Tredgold. 
25. History in Tools, by W. M. Flinders Petrie. 
26. The Background of Totemism, by HE. Washburn Hopkins. 
27. A Great Naturalist: Sir Joseph Hooker, by Sir H. Ray Lankester. 
