LIV GEELMUYDEN. ASTRONOMICAL OBSERVATIONS. [NORW. POL. EXP. 



the manner mentioned above, with y = 0. 9 IO and x only approximately 

 constant during the several intervals; in most cases the values obtained by 

 both methods are practically identical. 



If the adopted values of the clock error Hw Gr. are compared with the 

 corresponding values following from the eclipses of Jupiter's Satellites (Table c), 

 and the differences are grouped by D and R, the mean value, in the sense 

 obs. comp., is 14. 9 2 for D and + 13. 8 4 for R, according well with the 

 expectation that there would be a greater absorption of light in these high 

 latitudes, where the planet's average altitude is smaller than in Europe and 

 Australia. When the three periods of observation of Jupiter's Satellites are 

 considered separately, the mean difference R D is always positive; but it 

 must be added that the symmetrical division holds good only for the whole 

 mass of observations; if the same condition were to be fulfilled for each period 

 separately, the curve ought to be shifted about 17 s downwards at the begin- 

 ning of 1894 and 11 s upwards at the beginning of 1895. But during both 

 these winters the observations of D were so far less numerous than the ob- 

 servations of R that no correction could safely be deduced from this consi- 

 deration. For the last winter, where the observations of D are in excess and 

 the satellite points are on the whole much less dispersed, the condition of 

 symmetry is nearly fulfilled. 



The calculated values of Hw Gr. M. T. may of course be several 

 seconds in error and it is possible that this error may in some places reach 

 the amount of +20". An error of 20 s or 5' in longitude represents 1.6 km. 

 in latitude 80 and 0.8 km. in 85. 



Voyage along the Coast of Siberia. 



The astronomical observations taken before the enclosure in the ice have 

 all been reduced, not only because the track of the ship in these difficult 

 regions has an interest in itself, but also as forming the foundation for the 

 determination, by compass bearings, of the situation of numerous islands and 

 some points on the continent not to be found on previous maps. 



