February 21, 1902 ] 



SCIENCE. 



293 



proximatecl are the heliocentric coordinates 

 and their velocities, while in the present 

 method they are the geocentric distance 

 and the velocities of the heliocentric coor- 

 dinates, all for the zero date. (3) A short 

 method of obtaining preliminary values of 

 the geocentric velocities and accelerations 

 at the zero date. (4) A direct solution of 

 the fundamental equation of the seventh 

 degree in p„, on the basis of von Oppolzer's 

 table Xllla (' Bahnbestimmung,' Vol. I.). 

 (5) Differential formula for the deter- 

 mination of the final values of the helio- 

 centric coordinates and velocities from 

 which the elements are computed by 

 Encke's formula. Chief among the ad- 

 vantages of the method here outlined are 

 the ease with which such corrections to 

 /)„, xj, yj, «„' maybe determined asmll cause 

 the residuals due to the original values of 

 these quantities to disappear, and the pos- 

 sibility of determining these corrections 

 directly from the residuals. On that ac- 

 count, it is of no great consequence if the 

 originally adopted velocities and accelera- 

 tions in a and d are only approximate. 



Elements of Asteroid 1900 GA and its 

 Ephemeris for the Opposition of 1901- 

 1902: A. 0. Leuschner and Adelaide 



M. HOBE. 



This asteroid was discovered June 28, 

 1900, by the late director, James E. Keeler, 

 of Lick Observatory, while photographing 

 the region of the sky near Saturn with 

 the Crossley Reflector. Trails were photo- 

 graphed on four days and point-images on 

 two of these days. The problem of deter- 

 mining the orbit of the asteroid presents 

 many points of interest and has led to the 

 derivation of the ' Short and General 

 Method of Determining Orbits from Three 

 Observations.' The existing methods for 

 determining orbits could not be used to ad- 

 vantage in this case, but the solution was 

 successfully accomplished by means of the 



' Short and General Method of Determin- 

 ing Orbits from Three Observations ' out- 

 lined above. The magnitude of the asteroid 

 at the present opposition (1902, Jan. 4) is 

 19.5 ± .75. The asteroid is, therefore, the 

 faintest so far observed. The paper con- 

 cludes with the discussion of the residuals 

 of the measured positions of the termini 

 of the trails relatively to the middle of the 

 trails. 



Discovery of Motion in the Faint Nebula 

 Surrounding Nova Persei: C. D. Pbr- 



RINE. 



Early in the apparition of the new star 

 in Perseus, short exposure photographs of 

 it were secured with the Crossley Reflector 

 by Messrs. H. K. Palmer and C. G. DaU. 

 The first long exposure was secured on the 

 nights of November 7 and 8. This nega- 

 tive had a total exposure of 7 h. 19 m. It 

 was developed on the 9th, but omng to 

 stormy weather was not dry and was not 

 carefully examined until the morning of 

 the 10th, when it was compared with the 

 reproduction of a negative taken at the 

 Yerkes Observatory on September 20 by 

 Mr. Ritehey and published in the October 

 number of the Astrophysical Journal, and 

 the discovery at once made that several of 

 the principal condensations in the nebula 

 had moved to the southeast over a minute 

 of are in the interval. The main facts were 

 embodied in a telegram which was sent to 

 the Harvard College Observatory, for dis- 

 tribution to all observatories, at noon of 

 November 10. A negative was obtained on 

 the nights of November 12 and 13 with a 

 total exposure of ten hours. A more rapid 

 plate was used than on November 7 and 8 

 and with the longer exposure considerably 

 more detail is shown. An exposure of 5 h. 

 28 m. was obtained on the night of Decem- 

 ber 4. As a storm came on, this plate was 

 developed the following day. Considerable 

 detail was shown on the negative and three 



