( 108 ) 



We 



supposition b agrees exactly with the result of December 1903 which 

 was 59 s . 32, and on supposition c differs strongly from it, whence 

 appears clearly that the latter is less probable. It further appears that, 

 with regard to the three other stations, the results on the two extreme 

 suppositions b and c differ I s . 2 for Buku Zan and only s . 4 for 

 Mayili and Chimbete, while the results on suppositions a and b 

 differ for Buku Zan s . 2 and for Mayili and Chimbete less than s . 1. 

 The results from the two chronometers separately accord fairly well 

 inter se, Mayili excepted. 



As we reject the result of 1904 for N'Kutu and replace it by 

 that of 1903 and as for Mayili we can take the mean of the results 

 of 1902 and 1904, we find that the uncertainty caused in the final 

 results by the perturbation is less than was to be feared. 



Lastly I give here the final results obtained in this way, assuming 

 thereby the most probable supposition b : 



Difference of longitude with Chiloango 

 Mayili — l m 20 s .8 

 N'Kutu — 1 59.3 

 Buku Zan — 1 36 .2 

 Chimbete — 1 53 .3 

 The differences with the values adopted before are at the utmost s . 2. 



Astronomy. — "Observation of the transit of Mercury on November 

 14, 1907 at Chiloango in Portuguese West- Africa" . By 

 C. Sanders. (Communicated by Dr. E. F. van de Sande 

 Bakhuyzen). 



(Communicated in the meeting of May 30, 1908). 



For a short time I have possessed a telescope of Zeiss of 80 mm. 

 aperture and 120 cm. focal length. With this telescope I intend to 

 observe in the first place occultatious of stars in order to determine the 

 longitude of my observing station with greater precision than hitherto 

 has been possible. For the present the telescope has an azimuthal 

 mounting, which however soon will be replaced by an equatorial 

 mounting with slow motions and small divided circles. In the mean time 



