726 



SCIENCE 



[N. S. Vol. XLIV. No. 1142 



used as standards in other determinations of wave- 

 lengths. 



The fact that certain stars vary in brightness 

 has of course long been recognized, and there are 

 several papers here presented bearing on stellar 

 magnitudes or on variables, by Leon Campbell, 

 who comments on the rich and important contri- 

 butions being made by associated amateurs; by 

 Eussell, who brings out some exceedingly impor- 

 tant points from his treatment of eclipsing vari- 

 ables; by Shapley; by Kunz and Stebbins, who are 

 developing their photo-electric cells; by Seares, 

 who continues his contributions on the standard 

 photometric field of the polar sequence; and by 

 Parkhurst, who gives the results of his valuable 

 experience on the bases of photographic stellar 

 magnitudes. From various sources, important con- 

 tributions are now being made, showing that the 

 variation of light is not alone confined to the in- 

 tegrated light, but that marked changes of the 

 character of the spectrum are also involved. At 

 this meeting there were papers by Shapley, by R. 

 H. Curtiss, by Adams, and by Miss Cannon, on 

 this very fundamental matter. 



In other directions where constancy had come to 

 be regarded as perhaps the general condition, we 

 are now finding marked changes. Mr. Hubble 's 

 paper on a variable nebula presented photographs 

 of this remarkable object, showing that it had 

 undergone astonishing change of form. Whether 

 or not there is any relation between the change of 

 form and the light variation of the associated star 

 is not yet revealed. In 1914, at the Evanston 

 meeting of the society, Slipher showed his first 

 spectroscopic results, proving the rotation of cer- 

 tain nebulae. At this meeting, he presented 

 further evidence on the rotation of nebulas, and 

 contributions of similar nature were presented also 

 by Campbell and Moore, and by Pease. Lampland 

 gives evidence of rotation of two nebulas from 

 measurements of direct photographs. 



It was following the presentation of Pettit's 

 paper on the Circumstances of the Solar Eclipse 

 of June 8, 1918, that the committee to further the 

 cooperation in observing the eclipse was ap- 

 pointed. 



Very's papers on the albedoes of the Moon, the 

 Earth and the Planets, and the discussion which 

 followed, particularly that by Mr. Russell, did 

 much to clarify the ideas on this matter, where the 

 results by given observers have been at variance 

 and very perplexing. 



Professor Barnard has recently found a faint 

 star of about the eleventh photographic magni- 



tude which, in individual proper motion, exceeds 

 that of any heretofore recognized. In addition to 

 Barnard's paper on this star, Campbell and Moore 

 and also Adams contributed certain observations 

 on its motion. 



There have been very perplexing deviations in 

 the values for the rotation of the Sun, as deter- 

 mined by various observers using the spectro- 

 scopic method, and also from observations made 

 at different times by a single observer. The 

 papers by DeLury give a sufficient and positive 

 explanation of these deviations, and leave no rea- 

 son for supposing that the rate of rotation of the 

 Sun is variable from season to season. 



In a paper on the extension of Burnham's Cata- 

 logue of Double Stars, Doolittle summarizes the 

 work, which he has carried forward since Burn- 

 ham turned over his manuscript and material to 

 him. In doing this work, Doolittle is in a position 

 to state at once whether any double star suspected 

 of being new by any observer had already been 

 noted as such. He is also in a position to state 

 what objects have been recently and sufficiently 

 observed, and he offers to give information on 

 either of these points to any one who may wish to 

 profit by such service. Double star observers, to 

 work efficiently, must have information, at least 

 on the latter point, and to have available the in- 

 formation which Doolittle has at hand will mini- 

 mize the labor which its duplication would other- 

 wise necessarily involve. 



At the conclusion of the meeting, the following 

 resolution of appreciation of courtesies was 

 adopted : 



Sesolved: That the American Astronomical So- 

 ciety express to the President and Board of Man- 

 agers of Swarthmore College, its thanks for the 

 courtesies extended to the members of the society 

 during the meetings at Swarthmore. The society 

 desires also to express its appreciation of the 

 numerous arrangements made for their comfort 

 and convenience by Professor Miller and Presi- 

 dent Swain, and of the manner in which these have 

 been carried out by the matron of Wharton Hall 

 and others who have assisted in looking after the 

 welfare of the visitors. 



Sesolved: That the thanks of the society be ex- 

 tended to Senator William Cameron Sproul, to the 

 citizens of Swarthmore, to the president and trus- 

 tees of the University of Pennsylvania, and to the 

 president and board of managers of Haverford 

 College for their hospitalities in connection with 

 tne visit of the society and its appreciation of the 

 courtesies extended to its members. 



Resolved: That the secretary be directed to 

 communicate the substance of these resolutions to 

 Presidents Swain, Smith and Sharpless, and to 



others who have assisted. 



Philip Pox, 

 Secretary 



