May 26, 1905.] 



SCIENCE. 



811 



ores and of Western Coals for Northern Trans- 

 continental Survey, jmblished in Tenth U. S. 

 Census, and of numerous articles in the American 

 Chemical Journal, American Journal of Science 

 and Journal of American Chemical Society. 



Bailey Willis, E.M., C.E., Washington. Geolo- 

 gist; in charge of the stratigraphic geology de- 

 partment of the U. S. Greological Survey, and is 

 specially charged with the preparation of a geo- 

 logical map of the United States; in 1903-04 he 

 journeyed through Siberia and China under the 

 auspices of the Carnegie Institution to study the 

 geological history of those countries in compari- 

 son with that of North America, and is about to 

 extend his studies of mountain growth, etc., to 

 some of the European ranges. 



FOREIGN RESIDENTS. 



Yves Delage, Paris. Professor of zoology and 

 comparative anatomy at the Sorbonne; editor of 

 L'Annee Biologique ; author of ' La Structure du 

 Protoplasme et les Theories sur I'Hgr^dite,' Paris, 

 1895, and of numerous contributions to biology; 

 member of the Institute of France. 



Otto Xordenskjold, Stockholm. Eminent geog- 

 rapher and geologist; commanded Swedish Scien- 

 tific Expedition to West Antarctica in 1901-1903; 

 explored south and east coasts of Palmer Land, 

 Danco Land and King Oscar Land, and has made 

 numerous valuable contributions to knowledge in 

 geography, geology, paleontology and meteorology. 

 Author of ' Antarctic, tvii ar bland Sydpolens isar,' 

 published at Stockholm, and of many papers in 

 the Geographical Journal, La Geographic and 

 other scientific publications. 



William Matthew Flinders Petrie, D.C.L., LL.D., 

 F.R.S., London. Professor of Egyptologj' in Uni- 

 versity College, London; has made extensive ex- 

 cavations in Egypt and numerous important con- 

 tributions to Egyptian archeology; author of 

 'Pyramids and Temples of Gizeh (1883), ' Tanis ' 

 (2 vols., 1888-89), ' Naukratis ' (1886), 'History 

 of Egj-pt' (1894-96), 'Abydos' (2 vols., 1901- 

 02), etc. 



Edward Sievers, Leipzig. Professor of the 

 Grerman language and literature in the University 

 of Leipzig; an eminent authority in phonetics, 

 text criticism and meters ; author of ' Angelsa- 

 chsisclie Grammatik,' ' Phonetik,' ' Altgermanische 

 Metrik,' and of many other monographs. 



Sir William Turner Thiselton-Dyer, LL.D., 

 Ph.D., F.R.S., Kew, England. Eminent botanist; 

 director of Royal Botanic Gardens; botanical ad- 

 viser to the Secretary of State for the Colonies, 

 and has contributed very largely to the develop- 



ment of the botanico-economic resources of the 

 British Empire ; editor of ' Flora Capensis ' and 

 of ' Flora of Tropical Africa.' 



Afternoon Session— 2:30 O'clocTc. 



President Smith in the chair. 

 The Theory of the Double Suspension 



Pendulum: Professor R. S. Woodward. 



The double suspension pendulum is an 

 apparatus for determining the acceleration 

 of gravity. It consists of a massive 

 rectangular bar, which is held rigidly and 

 horizontally, and from which is suspended 

 a similar bar by means of two parallel 

 steel tapes of equal length. These tapes 

 pass through the bars and are clamped 

 rigidly to them. The tapes may thus be 

 regarded as elastic beams built in at both 

 ends. The suspended bar vibrates longi- 

 tudinally by reason of its weight and by 

 reason of the elastic bending of the tapes. 

 Measurements with the apparatus require 

 observations of the time of vibration of 

 the suspended bar and the lengths of the 

 suspending tapes. This form of pendulum 

 avoids entirely the difficulties of the knife 

 edges of ordinary pendulums and has the 

 additional advantage of superior steadiness 

 arising from the large vibrating mass. The 

 paper outlines the mathematical theory of 

 the motions of such a pendulum. 



The Relation Between the Economic Depth 

 for Bridge Truss and the Depth tvhich 

 Gives Greatest Stiffness: Professor 

 LIansfield Merriman, of Bethlehem, Pa. 

 The paper Avas read by the author. He 

 explained that the increase in the depth of 

 bridge trusses which has been going on for 

 the past fifty years was due to considera- 

 tions of economy and showed that there is 

 a certain depth which gives the minimum 

 amoimt of material. With respect to de- 

 flection under the passage of a train, it has 

 generally been supposed that this contin- 

 ually decreased as the depth of the truss 

 increased, but the author presented a proof 



