( 330 ) 



At tlie conjunction the elongations, counted along the orbit of 

 Jupiter, are equal ; they are to be found in the next cohnnn. If the 

 elongation is -|"' the satellite, as seen by a northern observer, using 

 a terrestrial telescope, will be to the left of the planet. Therefore 

 if he uses an inverting telescope, as is the rule for the observation 

 of the heavenly bodies, he will see it to the right. 



The three following columns contain the ordinates of the two 

 satellites and their difference; northerly latitudes are positive. The 

 tenth column shows the duration, which the eclipse would have, if 

 the conjunction were central. In a few cases (Nos. 20, 23, 30, 48, 

 53 and 64), we find ij = y, consequently ij — y = 0. If the tables 

 were correct these conjunctions would be central. But in testing the 

 tables by the conjunctions observed by Messrs Fauth, Kijland and 

 Stanley Williams the difference of the ?/'s did not completely agree 

 with the observations and even a small difference may considerably 

 change the duration of any eventual occultation. Therefore, not to 

 fill a column with figures, which, likely enough, may be contra- 

 dicted by the observations, I omitted the value found by calculation 

 for the true duration. 



We remarked before (p. 308) that, if at all, any conjunction will 

 be visible at a determined place of observation only for a short 

 time, viz. between sunset and the setting of Jupiter. As a conse- 

 quence the list will be of little use, unless observatories distri- 

 buted over the whole of the earth cooperate in the work. The last 

 column was added as a help to such cooperation. It contains on 

 every line an observatory, at which the conjunction of that line 

 will be visible. It is certainly desirable that other astronomers also, at 

 observatories in the vicinity, examine whether the phenomenon will 

 be visible, and, if so, prepare for its observation. 



