Apkil 1, 1904.] 



SCIENCE. 



54:^ 



make possible the election of associate mem- 

 hers as well as regular members; (2) to estab- 

 lish, for regular members, an entrance fee of 

 three dollars. 



The council was led to recommend such 

 action because of its desire to extend the ad- 

 vantages of membership in the Physical So- 

 ciety to a larger number of persons, and at 

 the same time to maintain a distinctly high 

 scientific standard in the case of the regular 

 membership. In the past the effort to accom- 

 plish both of these two aims has sometimes led 

 to considerable embarrassment, both to the 

 council and to membera making nominations. 



The policy of the council will hereafter be 

 to elect to regular membership in the society 

 only such persons as have contributed to the 

 advance of physics by investigation of a seri- 

 ous character. Those who have been prevented 

 from carrying out work of investigation, but 

 who are otherwise desirable as members of the 

 society, will be eligible for election to asso- 

 ciate membership. Associate members will 

 have all the privileges of membership except 

 that they may not vote nor hold office. They 

 will, for example, receive the two publications 

 now furnished by the society to its members. 

 Associate members may be transferred to reg- 

 ular membership by action of the council 

 whenever they have completed research work 

 of such character as to warrant such transfer. 

 It is not the policy of the council to make 

 election to associate membership a mere for- 

 mality for any who may desire it. On the 

 contrary, there is a strong feeling that the 

 society would best accomplish its object in 

 ' promoting the advance and diffusion of the 

 knowledge of physics ' by maintaining a high 

 standard for both regular and associate mem- 

 bership. 



The spring meeting of the society will be 

 held in Washington, on Friday, April 22, and 

 Saturday, April 23, 1904. Sessions for the 

 presentation of papers will be held on Friday 

 from 2 P.M. to 5 p.m., and on Saturday from 

 10 A.M. to 1 P.M. On Friday at 6 p.m. there 

 will be an informal dinner, and later in the 

 evening a lecture upon a subject to be an- 

 nounced later. On Saturday, at 1 p.m., a 

 luncheon by the Philosophical Society of 



Washington, complimentary to the Physical 

 Society. Saturday afternoon an excursion to 

 the Bureau of Standards and the Weather 

 Bureau. The arrangement of further details 

 regarding the meeting is in the hands of a 

 committee of the Philosophical Society of 

 Washington, at whose invitation the meeting 

 is held in that city. 



Brief abstracts of the papers read at the 

 February meeting are given below. 



The Conduction of Electricity in Mercury- 

 Vapor: A. P. Wills. 



This paper gave the results of an extended 

 study of the mercury vapor lamp carried out 

 in the Hewitt laboratory during the past year. 

 The measurements had especial reference to 

 the electromotive intensity in the positive 

 column. It was found possible to develop an 

 empirical formula representing with great ac- 

 curacy the dependence of the potential gradi- 

 ent upon current, pressure and diameter of 

 tube. The drop at the anode, usually about 

 seven volts, was found to rise under abnormal 

 conditions as high as fifteen volts. The drop 

 at the kathode was about five volts. 



Experiments Showing the Action of a Magnet 

 upon the Mercury Arc: Peter Cooper 

 Hewitt. 



Several very interesting experiments with a 

 large mercury vapor lamp were shown by Dr. 

 Hewitt. The action of a magnet upon the 

 positive column seemed to be about the same 

 as in an ordinary vacuum tube. The effect 

 upon the brilliant spot of light, or flame, at 

 the kathode was especially interesting. When 

 the lamp was in a rather strong field a lumin- 

 ous bundle of rays was seen to proceed from 

 the bright spot on the kathode surface, fol- 

 lowing a path that was the same as that of 

 the lines of force of the field. 



Microphotography of Fog Particles and the% 

 Photographic Study of Atmospheric Nuclea- 

 tion: Carl Barus. 



The author gave a description of his appara- 

 tus and methods, and illustrated the results 

 by a series of ten lantern slides and many 

 positives showing the microphotographs of fog 

 particles. Most of these were strikingly dis- 

 tinct, the water globules ranging in size from 



