44 REPORT OF NATIONAL MUSEUM, 1920. 



restaurants, apartment houses, and hospitals of Washington, that 

 they might select representatives to serve on the minimum wage con- 

 ference for this industry. The auditorium was also placed at the 

 disposal of Mrs. Susan Sipe Alburtis, in charge of nature study and 

 gardening courses in the Public Schools of the District of Columbia, 

 for lantern slide talks on trees, birds and gardens before children 

 of the public schools of south Washington, on March 3, 4 and 8, 

 there being no public school auditorium in the vicinity. 



The annual meeting of the National Academy of Sciences was held 

 in the Museum on April 20. 27, and 28, the auditorium being used 

 for the presentation of scientific papers in open session, and the 

 committee rooms for the business sessions. The William Ellery 

 Hale lectures on the evening of April 2G, by Mr. Harlow Shapley of 

 Mount Wilson Solar Observatory and Mr. Heber D. Curtis of Lick 

 Observatory, took the form of a discussion on " The Scale of the 

 Universe " and was exceedingly interesting. A conversazione fol- 

 lowed in the National Gallery of Art and the adjoining halls of the 

 Museum. 



Other speakers before the Academy and their subjects included: 

 John M. Clarke: Conservation of natural resources as a proper func- 

 tion of the National Academy ; Raymond Pearl : On the rate of 

 growth of the population of the United States since 1700 and its 

 mathematical expression; Franz Boas: Growth and development as 

 determined by environmental influences; Charles B. Davenport: 

 Plural births in man; Samuel J. Meltzer: The importance of the 

 presence of both sympathetic superior cervical ganglia to the main- 

 tenance of life, and their possible relations to respiratory diseases; 

 Charles D. Walcott: Structure of Marrella and allied Middle Cam- 

 brian crustaceans; James R. Angell : The National Research Council; 

 Robert M. Yerkes: A psychological study of the medical officers in 

 the Army ; Robert W. Wood : Spectroscopic phenomena of very 

 long vacuum tubes; L. T. E. Thompson, C. N. Hickman, and N. 

 Riffolt: The measurement of small time intervals and some appli- 

 ances, principally ballistic; Robert A. Millikan: The effect of molec- 

 ular structure upon the reflection of molecules from the surface of 

 liquids and solids; Arthur G. Webster: (1) The Springfield rifle and 

 the Leduc formulae, (2) Some new methods in internal ballistics of 

 the Springfield rifle, (3) Preliminary measurements on the pres- 

 sures in the " Onde de Choc," and (4) On the connection of the 

 specific heats with the equation of state of gas; George E. Hale: The 

 100-inch Hooker telescope of the Mount Wilson Observatory; A. A. 

 Michelson: (1) The vertical interferometer, (2) Preliminary tests 

 in an attempt to measure the diameter of the stars, and (3) A modi- 

 fication of the Foucault method adapted to long distance measure- 



