6l2 



SCIENTIFIC RESULTS OF ZIEGLER POLAR EXPEDITION 



As will be noted from the above tabulation, twenty-two Moon culminations were observed, 

 as also three occultations of fixed stars for the determination of longitude. These have been 

 reduced by the methods developed by Chauvenet.* 



The observed corrections at the Greenwich Observatory to the Moon's positions as given 

 by the Nautical Almanac have been kindly supplied by courtesy of the Astronomer Royal. In 

 accordance with Peirce's method of correcting the Ephemeris, formulae of the form X=A-\- 

 Bt + O' 2 for the various periods of observation have been derived by the method of least 

 squares, and the corrections at the particular times of observation computed therefrom. The 

 coefficients of the formulae are as follows: 



The corrections for declination in the case of the reduction of the occultations have been 

 determined graphically. 



The results for longitude are shown in the tabulations following, the various column head- 

 ings of which indicate the steps in the computations after the notation used by Chauvenet. 

 The mean results of this work are as follows : 



Mean longitude east of Greenwich of the astronomical observatory at Teplitz h m s s 



Bay derived from twenty-two Moon culminations 3 51 51.8 (1.3) 



Mean value derived from three occultations of fixed stars 3 51 58.6 (1.1) 



Weighted mean longitude east of Greenwich 3 51 52.6 ( 



This value is somewhat less than that obtained by the Italian Expedition when referred to 

 the same point. As stated above, the Italian astronomical station was not relocated ; a direct 

 comparison of the values may, however, be made by reference to the magnetic station occupied 

 by Commander Cagni. This station, which was 0.8 second of arc westf of the Italian 

 astronomic observing point, is 6.71 meters or o. i second of arc west of the astronomic observa- 

 tory of the Ziegler Expedition. The final result adopted from the observations of 1899 to 1900 

 was 3 U 52 16' ( 2') east of Greenwich, which, referred to the station of 1903 to 1905, would 

 be 3 h 52 1 5. "3. There is thus a difference between the two determinations of about 23 seconds 

 of time. It may be noted that the probable errors of the two values are of about the same 

 order. 



* Practical and spherical astronomy, by William Chauvenet. Philadelphia, 1885, 5th edition, volume I, 

 pp. 350 to 370 and 549 to 565. 



t Osservazioni scientifiche esequite durante la spedizione Polare di S. A. R. Luigi Amedeo di Savoia, Duca 

 degli Abruzzi. Milan, 1903, pp. 105 and 447. 



