222 



SCIENCE 



[N. S. Vol. XLII. No. 1076 



tirely to the immediate route, notes are given 

 on short side trips at two or three points. A 

 list of 45 publications on the region and a 

 glossary of geological terms are appended. 

 J. E. Hyde 

 ■Western Eeserve IjNryERSiTT 



FBOCEEDINGS OF TEE NATIONAL ACAD- 

 EMY OF SCIENCES 

 {NVMBEB 7) 

 The seventh number of volume 1 of the Pro- 

 ceedings of the National Academy of Sciences 

 contains the following articles : 



1. Nova Geminorum No. 2 as a Wolf-Bayet 

 Star: Walter S. Adams and Francis G. 

 Pease, Mount Wilson Solar Observatory, 

 Carnegie Institution of Washington. 



A continuous series of observations on Nova 

 Geminorum No. 2 has shown the development 

 of the spectrum of this star through the suc- 

 cessive stages characteristic of novag into one 

 very strongly resembling that of planetary 

 nebulas; and then by the gradual elimination 

 of the nebular lines and their replacement by 

 Wolf-Eayet bands, into a spectrum identical 

 with this characteristic type of stellar spectra. 



2. The Ruling and Performance of a Ten-inch 

 Diffraction Grating: A. A. Michelson, 

 Eyerson Physical Laboratory, University of 

 Chicago. 



A ten-inch grating (actual ruled surface 9.4 

 inches by 28 inches) having a theoretical re- 

 solving power of about 660,000 shows an actual 

 power of about 600,000. The method of ob- 

 taining exact ruling is also discussed. 



3. A Singular DarTc Marhing on the SJcy: 

 E. E. Barnard, Yerkes Observatory, Uni- 

 versity of Chicago. 



Erom a dark object in Cepheus and those in 

 Taurus the author gets the impression that 

 the interstellar spaces are suffused with a feeble 

 nebulosity and that the dark marks are due 

 to the projection upon this background of 

 nearer dark, opaque objects. 



4. A Highly Sensitive Electrometer: A. L. 

 Parson, Chemical Laboratory, University of 

 California, 



The principle of working in a condition 

 approaching instability is used to increase 



greatly the sensitiveness of electrometer and 

 obtain an instrument theoretically sensitive 

 enough to detect lO"" volt (though unsteadi- 

 ness makes it as yet impossible to detect an 

 isolated potential-difference of less than 

 3X10-= volt). 



5. The Distribution and Functions of Tribal 

 Societies among the Plains Indians: A Pre- 

 liminary Report: Clark Wissler, Ameri- 

 can Museum of Natural History, New York. 

 Eield-work conducted by the writer and his 



associates in the American Museum of Natural 

 History leads to the conclusion that the soci- 

 eties have spread from tribe to tribe by culture 

 diffusion of a desultory kind; that certain fea- 

 tures of organization are traceable to partic- 

 ular tribes, and no one tribe can be the 

 originator of the society as a whole. 



6. The Determination of Surf ace-Tension: 

 T. W. EicHARDS and L. B. Coombs, Woleott 

 Gibbs Memorial Laboratory, Harvard Uni- 

 versity. 



Attention is called to various sources of 

 error in the measurement and in the calcu- 

 lation of surface-tension by the capiUary-tube 

 method, an improved form of this method is 

 described, a new correction for the meniscus 

 is proposed, and exact measurements with a 

 number of liquids are presented. 

 1. An Exhibit in Physical Anthropology : Ales 

 Hrdlicka, Division of Physical Anthropol- 

 ogy, U. S. National Museum, Washington. 

 The exhibits prepared under the direction 

 of the author for the exposition at San Diego 

 are described brieily to indicate their breadth, 

 their permanent value, and their capability of 

 forming the foundation of an anthropological 

 center. 



8. The Compressibilities of the Elements and 

 Their Relations to Other Properties: T. W. 

 Eichards, Woleott Gibbs Memorial Labora- 

 tory, Harvard University. 

 This paper records all the recent work on 

 the compressibility of the elements performed 

 at Harvard, reduced to the best available stand- 

 ard — the newly determined compressibility of 

 mercury. It is pointed out that the reciprocals 

 of the melting points are very closely associated 

 with the coefficients of expansion, and that 



