( 308 ) 



Each of them represents a conjunction of two satellites. The corre- 

 sponding hours read off from the figure are : 



6«-2 : 



21 -8 : 



25 : 



35 : 



66 -25: 



71 -0 : 



YVf occulted by Illn, 



IV 



/ 

 III/ 



Iln, 

 II„, 



They were added to the instant which must be regarded as the 

 startingpoint for this figure. The instants of the conjunctions were next 

 converted into civil time of Paris by the addition of 12''9'"21s. 

 The elongation and the latitude of both the satellites, expressed in 

 radii of Jupiter, were then computed by the aid of the Tables édiptiques 

 of Damoiseau, 2nd part. (8). In the case that the elongations did 

 not perfectly agree, a slight computation led to a more accurate 

 resulf for the time of conjunction (9). 



In the case that the two satellites moved apparently in opposite 

 directions, (which happens if the one is in the further part of its 

 orbit, the other in the nearer part), the correction to the adopted 

 time was mostly insignificant. 



If, on the contrary, they moved the same way (which happens if 

 both are "far" or if both are "near", so that the one has to overtake 

 the other) the correction amounted sometimes to an hour or more. 

 In every case, in which the correction exceeded 20 minutes, the 

 computation was repeated with the corrected time. Further below 

 will be found the list of the results. From May 31 to July 19, i.e. 

 during a period of fifty days, there occur 72 conjunctions. It is to 

 be regretted that at a determined place of observation but very few 

 of them will be visible. For only those conjunctions are visible which 

 occur between sunset and the setting of Jupiter. For Utrecht we have, 

 in mean time : 



