670 



SCIENCE 



[Vol. LVI, No. 1458 



were secured, including complete skulls and skele- 

 tons a.nd their study is expected to throw mueli 

 light on the origin and dispersal of the higher 

 verteibrates and of men. 



The WUtney South Sea expedition of the 

 American Museum of Natural Sistory : Eobekt 

 Ctjshman Murphy (introduced by Frank M. 

 Chapman). For more than two years the Mu- 

 seum has been conducting ornithological investi- 

 gations in Polynesia. This paper summarizes the 

 purposes and accomplishments of the expedition, 

 and outlines some of the problems involved in 

 studying oceanic and insular zoology. 



Mutations among iirds in the genus Buarre- 

 mon: Frank M. Chapman. From a study of 

 the 160 specimens of Buarremon hrunneinucha 

 and B. inornata in the American Museum of Nat- 

 ural History the following conclusions arc 

 reached: (1) That Buarremon inornata is a rep- 

 resentative of Buarremon irunneinucha. (2) 

 That the variations dn pattern and color occurring 

 in the underparts of brunneinucha, throughout the 

 range of that species, are individual and are not 

 due^'to age, sex or season, to climate or other ob- 

 servable environmental factors. (3) That isola- 

 tion, partial or complete, has alone supplied tlie 

 conditions needful to the development and estab- 

 lishment of these characters as the specific at- 

 tributes of Buarremon inornata. 



On the attraction of a central body in the 

 theory of relativity: George D. Birkhofp. 



The equiaffine geometry of paths: Oswald 

 Veblen. 



The cosmological equation of gravitation: Ed- 

 ward Kasner. It is shown that the two sets of 

 equations introduced by Einstein in 1917 and 

 1919 are exactly equivalent in empty space. The 

 cosmological factor I can then be proved to be 

 a constant, instead of being so assumed. 



A theory of the various transverse effects of the 

 magnetic field in several metals: Edwin H. 

 Hall. 



The photo-luminescence of flames: E. L. 

 Nichols and H. L. Howes. When flames con- 

 taining salts of Na, Li, Ca, Ba, Sr, etc., are ex- 

 posed to light the bright bands in their spectra, 

 in general, are enhanced. The efEect, although 

 large compared to ordinary fluorescence, forms a 

 small part of the total brightness of tlie flame 

 and can not be readily detected except by speetro 

 photometric methods. As in ordinary photo- 

 luminescence excitation is by wave-lengths shorter 

 than those of the band itself. There is a meas- 

 urable quenching by exposure to the longer wave- 

 lengths and specifically to light identical with the 



band. So far as now known no new bands are de- 

 veloped as the result of excitation. The light 

 sources tJius far used as excitants are the tung- 

 sten lamp, carbon arc, mercury arc and iron 

 spark. 



The reflection of X-rays by crystals: "Williaii 

 Ditane. 



The analysis of certain crystals by the neto 

 X-ray method: G. L. Clark and William 



DUANE. 



The use of isophelimatic lines in historical geog- 

 raphy ; A new theory of population; A new hy- 

 drodynamical phenomenon; Further results in in- 

 terior ballistics: Arthur G-. Webster. 



The Thermal emissivity of loater : Mildred 

 Allen. 



The determination of ocean depths by acous- 

 tical methods: H. C. Hayes (introduced by W. 

 H. Dall and W. M. Davis). 



The gyroscope and its practical application in 

 the arts. Tiautern: O. B. Whitaker (introduced 

 by J. J. Carty and F. B. Jewett). 



Electronic tubes of high power: H. D. Ar- 

 nold, Ph.D. Eeceut developments in the con- 

 struction of high vacuum apparatus have made 

 possible the use of pure electron currents as large 

 as 30 amperes in single tubes which are capable 

 of controlling powers of 100 k. w. or more. This 

 paper discusses some of the problems in physics 

 and in engineering which were solved in the 

 course of this development, particularly those 

 which relate to the construction of glass and metal 

 apparatus suitable for use with these high powers. 

 The paper will be illustrated by samples of the 

 tubes and by slides showing tlie general features 

 of their construction. 



Carrier type multiplex telephony and teleg- 

 raphy: E. H. CoLPiTTS. The underlying 

 principles of carrier are discussed particu- 

 larly as they apply to carrier telephony, first, 

 where a single channel of communication is pro- 

 vided, and secondly, Where a number of chan- 

 nels are provided over the same pair of wires. 

 Apparatus is shown illustrating the various 

 physical steps in the process of transmitting 

 speech from one terminal statioai to the other. 

 Particularly the performance of filters in dis- 

 -criminating against the passage of currents out- 

 side of the band which they are designed to 

 transmit is demonstrated. In these demonstra- 

 tions use is made of a loud speaking telephone. 

 Spectrum energy curves of the stars: Charles 

 G. Abbot. 



Affine geometries of paths possessing an in- 

 variant integral: Luther P. Eisenhart. ■ 



