460 



SCIENCE. 



[N. S. Vol. XXIII. No. 586. 



Orhit of the Seventh Satellite of Jupiter: 

 R. T. Crawford and A. J. Champreux. 

 This paper gives results of an applica- 

 tion of Leuschner's 'Analytical Method of 

 Determining the Orbits of New Satellites.' 

 Three solutions were made which are 

 designated in the tabulation given below 

 by (Cr. & Ch.)i, (Cr. & Ch.), and (Cr. & 



tions in rectangular coordinates. With 

 these perturbations it is expected to repre- 

 sent recent observations closely. Outstand- 

 ing differences will serve to correct the 

 third set of elements. With each of the 

 three sets, a second solution with retrograde 

 motion was obtained. 



Harold Jacoby. 



ELEMENTS OF THE SEVENTH SATELLITE OF JUPITEE (DIRECT MOTION) REFEEEBD TO THE EARTH'S 



EQUATOR. 



Computer. 



(Cr. &Ch.)i 



(Cr. &Ch.)2 



(Cr. &Ch. )3 



Perrine (prel. ) . 

 Eoss (final) 



279 45 8 

 289 47 45 

 288 19 59 

 275 47 

 281 7.8 



26 27 14 

 25 39 42 



25 39 23 



26 15 

 26 12 



006 28 42 

 189 15 19 

 187 29 41 

 182 6 

 331 16.8 



0.12576 



0.13195 



0.12152 



0.24 



0.0246 



d 

 251.1415 

 255.5376 

 258.9424 

 200 

 265.0 



49 48 



50 20 

 50 47 

 43 48 

 52.54 



a (Cr. & Ch. ) for log (p) = 0.72124 ; a (Eoss) for log (p) = 0.71624. 



Ch.)3. The orbits are based on Perrine 's 

 positions of January 3, February 8 and 

 March 6, 1905. The first set of elements 

 was derived irrespective of any perturba- 

 tions. The second represents the first ap- 

 proximation to elements osculating Febru- 

 ary 8 by taking immediate account of the 

 attraction of the sun. The third set is the 

 result of a close representation of the ob- 

 servations on the same basis. For com- 

 parison, the elements by Perrine (L. 0. 

 Bulletin No. 78) and by Ross (L. 0. 

 Bulletin No. 82) are also tabulated. The 

 first set of elements does not represent an 

 observation of August 9 any better than 

 those by Ross. The third set, however, 

 gives the residuals {0 — C) : 



Ap = 4-2°.7 



As =+5' .2 



the computed positions being derived di- 

 rectly from the third set of elements oscu- 

 lating for February 8 without applying the 

 solar perturbations February 8 to August 

 9. The solar perturbations are being com- 

 puted for all observations secured since the 

 discovery observations, by an adaptation 

 of Encke's method of special perturba^- 



TBE AMERICAN ASSOCIATION FOB THE 



ADVANCEMENT OF SCIENCE. SECTION 

 A— MATHEMATICS AND ASTRONOMY. 



Vice-president — W. S. Eichelberger, United 

 States Naval Observatory, Washington, D. C. In 

 the absence of the vice-president, Professor Alex- 

 ander Ziwet, the retiring vice-president, presided 

 at the meetings of the section. 



Secretary — Professor L. G. Weld, State Uni- 

 versity of Iowa, Iowa City, Iowa. 



Mem.ber of the Council — President C. S. Howe, 

 Case School of Applied Science, Cleveland, Ohio. 



Sectional Committee — Dr. W. S. Eichelberger, 

 vice-president, 1906; Professor Alexander Ziwet, 

 vice-president, 1905; Professor L. G. Weld, secre- 

 tary, 1904-1908; Professor J. E. Eastman, one 

 year; Professor Ormond Stone, two years; Pro- 

 fessor E. B. Frost, three years; Professor E. O. 

 Lovett, four years; Professor Harris Hancock, 

 five years. 



Members of the General Committee — Professor 

 G. B. Halsted. 



Press Secretary — The secretary of the section. 



Dr. Edward Kasner, of Columbia Uni- 

 versity, was elected vice-president for the 

 year 1907. 



The address of the retiring vice-presi- 

 dent, Professor Ziwet, on 'The Relation of 

 Mechanics to Physics,' was presented on 

 the afternoon of December 29, in the gen- 

 eral assembly room in Gibson Hall, Tulane 



