426 



SCIENCE. 



[N. S. Vol. XV. No. :i76. 



University on Saturday, February 23. The 

 severe storm in tlie region near New York at 

 that time delayed the arrival of many of those 

 present, and doubtless prevented others from 

 coming. But the attendance was satisfactory 

 in spite of the storm, and the nieeting an 

 enjoyable one. 



A paper on the 'Velocity of Light,' by 

 President Michelson, took the place of the 

 president's annual address, which could not be 

 delivered at the holiday meeting of the Society 

 on account of Professor Michelson's unavoid- 

 able absence. The paper contained a brief 

 discussion of the various determinations of 

 the velocity of light, together with the de- 

 terminations of the ratio of the electrostatic 

 and electromagnetic units, and of the velocity 

 of electric waves. The conclusion was reached 

 that the great theoretical importance of 

 demonstrating, or disproving, the absolute 

 equality of these three quantities made a re- 

 determination of the velocity of light desir- 

 able. Certain criticisms, from the theoretical 

 standpoint, of the revolving mirror method, 

 which up to the present time has given the 

 most cpnsistent results for V, were also men- 

 tioned. A method was proposed which com- 

 bined the advantages of both the method of 

 Cornu, in which a toothed wheel was used, and 

 the method of the revolving mirror, as used 

 by Michelson and by Newcomb. While free 

 from the objections that have been suggested 

 in connection with the latter method, the 

 method proposed promises a higher accuracy 

 than has ever heretofore been reached. 



In a paper on ' Magneto-striction in Bis- 

 muth,' by A. P. Wills, experiments were 

 described which were intended to detect any 

 change in length in bismuth produced by 

 longitudinal niagTietization. Similar tests by 

 Bidwell had shown an appreciable elongation 

 for a magnetic field of less than 2,000 c. g. s. 

 units. The experiments of Professor Wills 

 were made with a stronger field and with an 

 arrangement of levers of sufiicient sensitive- 

 ness to show a much smaller elong-ation than 

 that reported by Bidwell; but no effect could 

 be observed. 



In a paper entitled, 'The Transmission of 

 Sound Through Solid Walls,' Mr. F. L. Tufts 



gave the results of determinations of the 

 transmitting power for sound of various non- 

 porous walls. The results were in many 

 respects different from what would probably 

 be anticipated from a hurried consideration 

 of the case. For example, a wall of sheet 

 lead, in spite of its great density and its lack 

 of elasticity, was found to transmit much 

 more sound than a glass wall of equal thick- 

 ness. Two walls separated by an air space 

 were no more effective in cutting off sound 

 than the same two walls in contact. The 

 results indicate that the sound is transmitted 

 in such eases by the forced vibration of the 

 wall as a whole, not by the elastic waves car- 

 ried through the wall. Other things being 

 equal, that medium which yields most to 

 pressure steadily applied will transmit best. 



Professor A. G. Webster, in a paper on the 

 'Spherical Pendulum,' showed some very 

 pretty traces illustrating the vibrations of a 

 pendidum whose motion is not restricted to 

 one plane and whose amplitude is large. The 

 traces were made by photographing the path 

 of a small incandescent lamp attached to the 

 pendulum bob. The theory of such a pendu- 

 lum was briefly discussed, and it was shown 

 that the traces actually observed were in close 

 agreement with those predicted by theory. 



Certain distorted coronas, produced by a 

 medium containing drops of moisture of dif- 

 ferent sizes, were described by Carl Barus in 

 a paper entitled 'The Flower-like Distortion 

 of Coronas Due to Graded Cloudy Condensa- 

 tion.' The author developed the theory of 

 such coronas and showed that it was in agree- 

 ment with observation. 



A second paper by Professor Barus dealt 

 with 'Persistent Nuclei Produced by Shaking 

 Solutions of Solids, Liquids or Gases.' The 

 author stated that whereas the nuclei pro- 

 duced by pure water were very fleeting, nuclei 

 produced by solutions persisted until removed 

 by gravity. It follows that small droplets of 

 solutions do not evaporate below a certain 

 dimension, very large compared with molecu- 

 lar dimensions. 



The results of measurements of the current 

 between a cold metal and an incandescent 

 carbon kathode were presented in a paper by 



