ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably prepared 

 and signed by themselves, are forwarded promptly to the editors. The abstracts should 

 conform in length and general style to those appearing in this issue. 



PHYSICS. — TJie efflux of gases through small orifices. Edgar Buckingham 

 and J. D. Edwards. Bur. Standards Sci. Paper 359. Pp. 47, figs. 

 7. 1920. 



This paper contains a theoretical discussion of the results of experiments 

 made during an investigation of the effusion method of determining gas den- 

 sity. The effects on effusion of viscosity and thermal conductivity of the 

 gas are studied, and formulas for representing these effects are developed and 

 compared with the observed facts. A physical interpretation is thus obtained 

 for the most striking of the apparent anomalies observed in the behavior of 

 gases flowing through very small orifices such as are used in apparatus for 

 determining density by effusion. The resulting agreement of the theory 

 with the observations is exhibited graphically. It is fairly satisfactory 

 but not perfect, and its imperfections suggest the directions in which further 

 experiments should be made. J. D. E. 



PHYSICS. — The constants of radiation of a uniformly heated enclosure. W. W. 

 CoBLENTz. Bur. of Standards Sci. Paper 357. Pp. 11. 1920. 



Experimental data are given on atmospheric absorption. The paper gives 

 also a recalculation of the coefficient of total radiation of a uniformly heated 

 enclosure, or so-called black body, giving a value of 5.72 X 10~^^. The 

 eft'ect of atmospheric absorption is discussed, and the conclusion arrived at is 

 that, if corrections are made for atmospheric absorption, the value recently 

 obtained at Naples is close to the average value, viz., 5.7. In the second part 

 of the paper, the present status of the constant of spectral radiation is dis- 

 cussed. W. W. C. 



PHYSICS. — An integration method of deriving the alternating current resistance 

 and inductance of conductors. H. L. Curtis. Bur. Standards Sci. 

 Paper 374. Pp. 35, figs. 4. 1920. 



The solution of the problem was met by a process of integration. The 

 conductor is divided into infinitesimal filaments by surfaces which coincide 

 with the lines of flow. The magnetic field at any point is the sum of the 

 magnetic fields of all these filaments. The counter-electromotive force in a 

 filament is determined by the rate at which the magnetic fields of all the others 

 cut this filament. 



Formulas for the alternating current resistance and inductance of a straight 

 cylindrical conductor were derived by the use both of real and imaginary 

 power series. These formulas correspond exactly with the asymptotic form- 

 ulas of Russell. The same method is applied to a return circuit making use 

 of imaginary series, and formulas for the alternating current resistance and 

 inductance are derived. Values computed by these formulas are compared 

 with experimental results. H. L. C. 



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