166 



SCIENCE 



[N. S. Vol. XL VI. No. 1181 



as it should have been. It, of course, was im- 

 possible, or rather impracticable, to extend a 

 precise level net into areas through which rail- 

 roads had not been run, for the expense would 

 have been prohibitive. It may be that the Sur- 

 vey did not fully realize the necessity for hav- 

 ing all engineering and surveying work on the 

 same datum, but in recent years it has become 

 fully alive to the necessity of having a single 

 datum for the entire country, and it is conse- 

 quently extending its precise leveling net as 

 rapidly as funds available will permit. 



While it is of value to the nation for various 

 organizations and individuals to adopt and use 

 mean sea-level datum for their elevations, the 

 country will benefit still more if each organi- 

 zation doing extensive leveling will publish in 

 pamphlet form the elevations and descriptions 

 of the bench marks they may establish in order 

 that other organizations and individuals may 

 properly coordinate their levels. Engineers 

 are urged also to use substantial bench marks 

 in order that future work may be benefited by 

 their preservation. 



The amount of precise leveling which should 

 be done by the federal government can not be 

 foretold. It must dejpend upon the needs of 

 the various organizations and individuals 

 using the results. After a certain development 

 of the precise level net which appears now to 

 be absolutely necessary, the rapidity with 

 which further extensions are made should de- 

 pend upon the development of the country. 

 But such further extensions should precede 

 rather than follow such development, as is 

 proved by the unfortunate condition of affairs 

 in much of our engineering and surveying 

 work, due to lack of precise elevations in the 

 past, when such work was inaugurated. 



This paper on mean sea level should, and no 

 doubt will, do much good in furthering the 

 universal adoption of mean sea level as the 

 reference surface for all elevations. 



The publication of such pamphlets by gov- 

 ernment organizations is to be commended, 

 for they present facts to the public in an ef- 

 fective way which may otherwise be buried 

 for years in valuable but more cumbersome 

 government reports with which all of us are 

 more or less familiar. William Bowie 



PROCEEDINGS OF THE NATIONAL 

 ACADEMY OF SCIENCES 



The sixth nimiber of volume 3 of the Pro- 

 ceedings of the National Academy of Sci- 

 ences contains the following articles : 



The stark effect in helium and neon : Harry 

 !N"yquist, Sloane Laboratory, Tale University. 

 An improvement of Lo Surdo's method is 

 applied. 



New analyses of echinoderms: F. W. 

 Clakke and E. M. Kamm, United States Ge- 

 ological Survey, Washington. A progressive 

 enrichment in magnesia, following increase 

 of temperature, is unmistakable. 



On utilizing the facts of juvenile promise 

 and family history in awarding naval com- 

 missions to untried men: C. B. Davenport, 

 Station for Experimental Evolution, Carnegie 

 Institution of Washington. A study with 

 family charts of a number of naval officers. 



The triplet series of radium: Gladys A. 

 Anslow and Janet T. Howell, Department 

 of Physics, Smith College. 



The measurement of small angles hy dis- 

 placement interferometry : Carl Barus, De- 

 partment of Physics, Brown University. 



Mechanisms that defend the hody from 

 poliomyelitic infection, (a) external or extra- 

 nervous, (fc) internal or nervous: Simon 

 Flexner, Eockefeller Institute for Medical 

 Research. A report upon the results of re- 

 cent experiments. 



The occurrence of harmonics in the infra- 

 red ahsorption spectra of diatomic gases: 

 James B. Brinsmade and Edwin C. Kemble, 

 Jefferson Physical Laboratory, Harvard Uni- 

 versity. The discontinuities in the structure 

 of these bands force the conclusion that the 

 angular velocities are distributed among the 

 molecules in the discontinuous manner pre- 

 dicted by the older form of the quantum 

 theory, and the proved existence of harmonics 

 is almost equally good evidence that the vibra- 

 tional energy of the molecules is distributed 

 in the same manner. 



The loss in energy of Wehnelt cathodes 

 hy electron emission: W. Wilson, Research 

 Laboratories of the American Telephone and 

 Telegraph Company and of the Western 

 Electric Company. The emission of the elec- 



