June 18, 1920] 



SCIENCE 



619 



(Introduced by Professor Robert G. Aitken.) The 

 paper summarizes in non-teclinical terms the evi- 

 dence afforded by a study of the stellar condensa- 

 tions in the planetary or small gaseous nebulse, 

 which are shown to be spectroscopically identical 

 with stars of the Wolf-Eayet group (Pickering's 

 Glass O). A brief account is given of some of the 

 present day conceptions of stellar evolution, for 

 the purpose lof indicating the somewhat critical 

 nature, with respect to these ideas, of the relation- 

 ship indicated. A complete account of the investi- 

 gation, of which the paper summarizes a part, is 

 given in Volume XIII., part 6, of the Publications 

 of the Lick Observatory. 



The Eiristein theory: Edwin Plimpton Adams, 

 Ph.D., professor of physics, Princeton University. 

 Following Newton's statement of the law of uni- 

 versal gravitation, the goal of all physical explana- 

 tions of natural phenomena was to reduce them to 

 actions at a distance between elements. After 

 MaxrweU showed that electric and magnetic phe- 

 nomena could be accounted for by a system of 

 pressures and tensions in a universal medium — ^the 

 ether — the goal changed, and the attempt was made 

 to explain physical phenomena, by direct action 

 through a medium. Attempts to account for gravi- 

 tational forces, however, in this way met with little 

 success. The extension, hj Einstein, of the prin- 

 ciple of relativity and the resulting revision of 

 the concepts of space and time, led to Einstein's 

 interprertation of gravitation as a property of space 

 itself when modified by the presence of matter. 

 ; The results of geophysical observations during 

 the solar eclipse of May S9, 1919, and their bea/r- 

 ing upon the Einstein deflection of light. (Illus- 

 trated) : Louis A. Bauer, Ph.D., Sc.D., director of 

 the department of terrestrial magnetism, Carnegie 

 Institution of Washington. This paper is a con- 

 tinuation of the one presented at a stated meeting 

 of the society on February 6, 1920. In that papen 

 a r&ume was given of the geophysical and astro- 

 nomical observations concerning the solar eclipse 

 of May 29, 1919, and the Einstein effect made by 

 the various expeditions sent out by the Depart- 

 ment of Terrestrial Magnetism of the Carnegie In- 

 stitution of Washington and the various astronom- 

 ical expeditions sent out by Great Britain, the Rio 

 Janeiro Observatory, and the Smithsonian Insti- 

 tution. It was shown how the results of the geo- 

 physical observations may have an important bear- 

 \ 1 " Observations in Liberia and Elsewhere of the 

 •Total Solar Eclipse of May 29, 1919, and Their 

 Bearing on the Einstein Theory. ' ' 



ing upon the complete interpretation of the astro- 

 nomical observations showing the deflections of 

 light during the eclipse. A brief analysis of the 

 light deflections was given and it was pointed out 

 that there were non-radial effects of such a syste- 

 matic nature that they could not be accounted for 

 by errors of observation. The present paper gives 

 the results of a special study of the cause of the 

 non-radial effects of the light deflections observed 

 by the British expedition at Sobral, Brazil. It is 

 shown that these non-radial effects may be com- 

 pletely accounted for by incomplete elimination of 

 differential refraction effects in the earth's atmos- 

 phere. The same cause may apparently also ex- 

 plain why the observed radial deflections of light 

 exceeded, on the average, by about 14 per cent, the 

 amounts predicted on the basis of the Einstein law 

 of gravitation. 



The high voltage corona in air: J. B. White- 

 head, professor of applied electricity, Johns Hop- 

 kins University. (Introduced by Dr. Pender.) 

 The paper describes the nature of the corona and 

 recent studies of the laws governing its appearance 

 in high voltage circuits. Its influence as a limiting 

 factor in long distance transmission occurs through 

 deterioration of insulation and a leakage loss of 

 power between the high voltage lines. The appear- 

 ance of corona on a clean round wire is very 

 sharply marked and may be used for the measure- 

 ment of high alternating voltages to a degree of 

 accuracy not heretofore possible. Experiments and 

 observations on the corona voltmeter, an instrument 

 devised for this purpose, are recorded; and an ex- 

 ample of the instrument, suitable for voltages up 

 to 300,000 volts, is described. 



The velocity of explosive sounds: Datton C. 

 MiLLEE, D.Sc., professor of physics. Case School 

 of Applied Science, aeveland. In 1918-1919 the 

 writer had the privilege of making an extended 

 series of experiments on the pressure waves from 

 large guns in action, at Sandy Hook Proving 

 Ground. One series of experiments was for the 

 purpose of determining the variation in the veloc- 

 ity of the sound of the gun explosion as measured 

 from the muzzle outward, and for the determina- 

 tion of the velocity of sound in free air. Most of 

 the experiments were made in connection with 10- 

 ineh and 12-inch rifles, though a few were made 

 with 6-inch and 8-inch guns. The amount of 

 powder charge and the value of the internal pres- 

 sure developed in the gun are taken into account. 

 The sounds were received iby means especially con- 

 structed carbon-granule microphones, while others 



