I. — Astronomic Observations. 



Although this completely agrees with thu mean teiiour of the other 

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

 mean of each day, we get as general mean : 



11th July, 8" 42"' C„„= +5" 15" 33=- 1. 



From the observations taken at Bujongolo during the days following our 



arrival we had (see p. 311) : 



28th June, 20" 25"' C„„= + S" 15"" 28»-l. 



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,„. = + S" 1 5"" 33^-3 



Moment of Occultation „ = +5*" IS" 33''-2 



With this element and with the approximate longitude already cjbtained, 

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

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

 chronometer indicated 10" 14™ 4* (Olis. No. 55). From the first approximation 

 we got : 



Bujongolo \ = 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 \ery slightly modified the result. 



Thus : 



Bujongolo \ = 1" 59" 59'- 33 E.G. 



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

 affected liy 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 

 oliservations of lunar cnlminations had concurrently lieen 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 Romano, 

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

 where the astronomer. Dr. Bianchi, was obser^•ing transits of the moon at 

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

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

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

 the moon= -i-0*-18, and this agrees perceptilily with that communicated to us 

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



It may be mentioned that Greenwich also supplied us with the cori-ection 

 for that date of the lunar dediniition = + P-8. 



313 



