( 454 ) 



The explanation of these extravagant differences mnst rather he 

 songht, either in a correction needed l\y the longitude of the node 

 of the satellite's orbit or in the adopted tlattening of Jupiter. It is 

 also possible that for suchlike eclipses the diminution of light is 

 very slow. 



For tlie rest, according to the Nautical Almanac, this eclij^se 

 would be the fourth after the long period in which no eclipse of 

 this satellite occurred. The data, on pages 450, 452, 454 are as 

 follows : 



1895 

 17 Jan>'. D. 1'' 36^16^ M. T. Gr., R. 2^ 8'"17^ duration 32-^1 1« 



2 Feb>. „ 19 26 12 „ „ „ „ 20 36 58 , „ 1'' 10 46 



19 „ „ 13 24 6 „ „ „ „ 14 59 3 , „ 1 34 57 



8 March „ 7 24 14 „ „ „ „ 9 18 28, „ 1 54 J4. 



Only, according to Scott-Hansen, who, on the North-Polar expedition 

 of Nansen, was in charge of the astronomical observations, the 

 satellite has not been eclipsed at all on the 17^'^ of January ^). 



On the 2 "f^ February 1895 too an eclipse of IV was not observed; 

 (I cannot now call to mind where I saw this negative observation). 

 On the 19^'' February, however, an observer at Greenwich, using the 

 Sheephanks equatorial, aperture 120 mm., got a correction of -|- 23'"30s, 

 for the disappearance of IV. This agrees quite well with the preceding 

 results, obtained at Uccle and at Jena on 8''^ of March. 



If we adopt the mean result of the observations at Brussels and 

 at Jena, the duration of the eclipse on that day was 

 Xh44mi4s _ 39m57.s 5 _ li.i4mie%5, 



The number might be of some use for the correction of the ele- 

 ments of IV. 



The difference here found cannot be attributed to a too small value 



of the adopted flattening, for Damoiseau's value -r— r exceeds already 



that found by direct measurement by most observers. Taking into 

 account however the results obtained by De Sitter, as communicated 

 at the meeting of the Section (Proceedings Vol. VIII p. 777), it 

 appears that the longitude of the ascending node of the 4^^^ satellite 

 must be increased by about -\- 10°, whereas for the inclination on 



1) The Norwegian North Polar Expedition 1894-1896. Scientific Results, edited 

 by Fridtjof Nansen. VI. Astronomical Observations, arranged and reduced under 

 the supervision of H. Geelmuyden, p. XXIV. 



