492 



SCIENCE. 



[N. S. Vol. IX. No. 322. 



fessor Gerhardt and Generaloberartzt Schjern- 

 iug, of Berlin ; (4) 'Therapy,' by Professor von 

 Ziemssen, of Munich, and ProfessorSchroetter, of 

 Vienna ; (5) ' Sanitaria,' by Herr Gaebel,. Presi- 

 dent of Imperial Insurance OflSce, Berlin, and 

 Dr. Dettweiler, of Falkenstein. 



Following the presentation of the two lead- 

 ing papers (limited to 20 minutes each) in the 

 respective divisions, there will be a general 

 discussion, speakers being limited to 10 minutes 

 each. All papers and remarks are to be in 

 German, although the chairman is empowered to 

 make exceptions during the general discussion. 



All persons interested in the subject of tuber- 

 culosis are eligible for membership; membership 

 cards (20 Marks, nearly $5) are to be obtained at 

 the office of the Congress (' Bureau des Organi- 

 sations-Komites, Wilhelm Platz 2, Berlin, W) 

 and entitle the bolder to a copy of the ' Proceed- 

 ings.' An early registration is requested. 



The writer has been requested to furnish a 

 list of Americans to whom special invitations 

 to the Congress should be sent. He has com- 

 plied with this request, so far as his personal 

 and professional acquaintance with specialists 

 in this line has permitted, and has also sug- 

 gested to the committee that invitations be sent 

 to the various medical societies and faculties. 

 There are undoubtedly many American practi- 

 tioners especially interested in tuberculosis and 

 possibly some laboratory workers whom he has 

 overlooked. Should any such person desire to 

 attend the Congress, yet prefer to receive a per- 

 sonal invitation, the writer will be pleased to 

 forward the name of such persons, upon proper 

 introduction, to the Executive Committee of 

 the Congress. As 'proper introduction ' will 

 be considered a letter from any recognized med- 

 ical, scientific or veterinary faculty or society. 

 Ch. Waedell Stiles, Ph.D., 



Scientific AttachS, U. S. Embassy, Berlin, Ger- 

 many. 



ASTRONOMICAL NOT^S. 



THE EUTHEEFURD PHOTOGEAPHS. 



Among recent additions to the literature of 

 the astronomy of precision are four contribu- 

 tions from the Observatory of Columbia Univer- 

 sity which give the results of measurements of 

 the Rutherfurd plates. Dr. Davis contributes 



three of these, entitled 'Catalogue of Sixty-five 

 Stars Near 61 Cygni,' 'The Parallaxes of 61' 

 and 612 Cygni,' ' Catalogue of Thirty-four Stars 

 near Bradley 3077.' Mr. Scblesinger contrib- 

 utes the fourth, upon 'The Prsesepe Group.' 

 All these are most admirable illustrations of the 

 highest type of astronomical work in the de- 

 termination of exact positions of the stars, and 

 careful deductions therefrom. No pains have 

 been spared to make the original measures un- 

 der such conditions that the instrumental con- 

 stants shall be well determined, and all cor- 

 rections and reductions accurately applied. The 

 result is three catalogues of stars whose coordi- 

 nates relative to the reference star in each group 

 are determined with great precision. The two 

 catalogues of stars near 61 Cygni and Bradley 

 3077 are for the purpose of discussing the paral- 

 laxes of these well-known stars. The most in- 

 teresting result of Dr. Davis's discussion is the 

 well-marked difference of parallax between 61' 

 and 61^ Cygni, determined from both position 

 angles and distances, the numerical amount of 

 which is 0".072 ± 0".028. This large difference, 

 if real, explains the failure of double-star ob- 

 servers to detect any evidence of orbital motion, 

 and would show that the stars do not form a 

 binary system. A confirmation of this conclu- 

 sion is found in a careful discussion of Wilsing's 

 determinations of the distance of these two 

 stars, which gives 0".0876 for the difference. 

 The mean of the different determinations of 

 parallax for the stars made by other astrono- 

 mers shows a difference of 0".082, which con- 

 firms further the reality of the result. The 

 author urges the making of a more extended 

 series of comparisons by photography to give 

 further evidence on this subject. 



An interesting result of Mr. Scblesinger's 

 study of the measures of the Priiesepe stars is 

 that the method of orienting the plate by the 

 method of trails is not as accurate as that ba ed 

 upon assuming the coordinates of several com- 

 parison stars on the plate, as determined by the 

 meridian circle or the heliometer. It was Mr. 

 Rutherfurd's rule to make two impressions of 

 the regions photographed, stopping the clock 

 for a few seconds between them, and also to 

 give a third impression of the brightest stars 

 by stopping the clock about three minutes and 



