I. — Astronomic Observations. 



Although this completely ugfees with the mean teuour of the other 

 results, the last value is for the present neglected, and, after obtaining the 

 mean of each day, we get as general mean : 



11th July, SM2"" C,„,= +5'' 15"^ 3:V-l. 



From the observations taken at Bujoiigolo during the days following our 



a,rrival we had (see p. 311) : 



28th June, 20'> 25"' C,„,= + o'^ 15" 28^-1. 



Hence for this interval of 12-52 days we obtain the diurnal correction : 



K= +0^-398 

 with which we get : 



12th July, 0'^ of local time C„„= +5'^ 15™ 33^-3 



Moment of Occultation „ = +5'^ 15" 33^-2 



With this element and with the approximate longitude already obtained, 



we proceed to a first calculation of mean Greenwich time at the moment of 



emersion of B AC 81 from the lunar disk, the moment when the No. 1 



■chronometer indicated 10'' 14'" 4^ (Obs. No. 55). From the first approximation 



we got : 



Bujongolo A= P 59" 59^- 2 E.G. 



The calculation for a second approximation, in which account was also 



taken of the terms of second order, only very slightly modified the result. 



Thus : 



Bujongolo \ = P 59" 59^- 33 E.G. 



As, however, the value of the longitude thus obtained might be seriously 

 <iffected l»y even a slight error in the lunar co-ordinates given by the 

 ephemerides, we consulted some astronomic observers in order to ascertain 

 whether, about the time when the expected occultation took place, any 

 observations of lunar culminations had concurrently been made. This was 

 done in order to introduce into the calculation the error of the position of 

 the moon. 



Prof. Millosevich, Director of the Observatory of the Collegio Eomano, 

 in Home, having undertaken the determination of the longitude of Tripoli, 

 where the astronomer, Dr. Bianchi, was observing transits of the moon at 

 meridian, proceeded to take oljservations of lunar culminations at the Collegio 

 Romano from the 2nd to the 7th Jul}-, 1906. From these he obtained for 

 11th July— time of the occultation — a correction for the right ascension of 

 the moon= +0^-18, and this agrees perceptibly with that communicated to us 

 by Greenwich for the same date = + 0^*20. 



It may be mentioned that Greenwich also supplied us with the correction 

 for that date of the lunar declination = + P'8. 



313 



